The U.S. Special Operations Command (USSOCOM), through Naval Surface Warfare Center Crane Division (NSWC Crane), has issued a solicitation seeking a new lightweight, man-portable, belt-fed 5.56x45mm machine gun to eventually replace the aging MK46 series. The HICAR program rifle would also accompany this, as they are intended to use standard 5.56x45 ammunition and the M855A1+ hypervelocity ammunition. The effort, identified as the FAMG opportunity, aims to develop a weapon that preserves the mobility and suppressive-fire capabilities expected of a light machine gun while tailoring it for the assault and leveraging modern materials, manufacturing techniques, and weapon technologies.

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The requirement is an ambitious small-arms development challenge: balance reduced weight and improved maneuverability and controllability without sacrificing reliability or durability. USSOCOM wants the replacement weapon to let operators shoot, maneuver, and provide effective suppressive fire, and extend the range out to 500 m.

The solicitation emphasizes portability. The proposed FAMG must weigh no more than 11.5 pounds with a goal weight of 10 pounds. The weapon is also limited to a maximum overall length of 39 inches with the stock collapsed, with 35 inches as the desired goal.

The FAMG is expected to use a Safe/Automatic fire-control FCG, although a Safe/Semi-Automatic/Automatic arrangement is also considered acceptable or most likely preferred. A minimum cyclic rate of fire of 400 and a maximum of 650 rounds per minute.

Reliability

Perhaps the most demanding portion of the solicitation concerns reliability. The required Class I Mean Rounds Between Stoppages (MRBS) is 1,400 rounds, with a target exceeding 2,000 rounds. The weapon must also achieve at least 1,800 rounds for Class I Mean Rounds Between Essential Function Failures (MRBF).

For more severe classes of failures, the requirement rises substantially to class II or III MRBF must be at least 15,000 rounds.

The solicitation calls for a mature system that can demonstrate substantial reliability during testing. Indeed, proposers must already have a minimum Technology Readiness Level (TRL) of 7, meaning the proposed technology must be mature enough to support a demonstrated prototype rather than merely an early-stage concept.

Accuracy, Recoil and Endurance

The FAMG must have an effective range of at least 500 meters against area targets. Secondary requirements address dispersion, calling for an Average Extreme Spread of no more than 10 MOA for single shots and 11 MOA for bursts at 100 meters.

Recoil management is another significant theme. The solicitation states that recoil impulse should be sufficiently low to permit effective employment of the weapon throughout its maximum effective range, both during daytime and nighttime operations. This means designers may use a constant recoil design.

The government also places substantial demands on durability. Developmental testing should demonstrate a receiver life of at least 100,000 rounds, with 200,000 rounds identified as an objective. Barrel life is similarly specified at 15,000 rounds, with 20,000 rounds as the desired goal, so an ARMAD material or similar could meet these requirements.

These requirements put the FAMG in an interesting engineering conundrum where the weapon must be lighter than the system it replaces while offering long component life and high reliability. This would be achieved through good design and by leveraging new materials.

Barrel

The solicitation calls for a quick-change barrel that can be replaced in 30 seconds or less. The design must also provide substantial mounting space for accessories and enablers. The requirement specifies 15 inches of MIL-STD-1913 rail at the 12 o’clock position and seven inches at the 6 o’clock position, along with usable M-LOK mounting locations on the sides of the handguard.

Compatibility with modern sighting and targeting equipment is specifically addressed. The FAMG should support machine-gun optics, clip-on night-vision devices, aiming lasers, and fire-control systems while maintaining appropriate eye-relief considerations.

The design must also accommodate the practical requirements of a belt-fed weapon. It should support left-hand ammunition feeding and securely retain ammunition on the feed tray when the top cover is open. It should include an ammunition storage mounting point (equivalent to MK46) and ammunition storage system that can secure a minimum of 100 linked 5.56mm rounds.

Ergonomics and Mobility

USSOCOM’s requirements extend beyond raw performance figures. The weapon is expected to feature a collapsible stock that locks securely into position while still allowing the weapon to be charged and fired. A side-folding stock is Not requested, this is aimed at keeping the weight down. A two-position/folding charging handle is also required, though this typically leads to a weak point that can break more easily than a fixed charging handle.

The bipod must deploy and stow rapidly, adjust for height, and remain stable enough to support firing across the weapon’s effective range. The solicitation specifically calls for the bipod to lock when loaded, preventing unwanted pan and tilt.

The FAMG must also integrate with existing pintle and swing-arm mounting systems. Muzzle devices are expected to be removable at the organizational level using standard tools.

Environmental and Safety Requirements

Environmental testing is another significant component of the program. The weapon should experience zero stoppages after exposure to temperatures ranging from -20°F to 165°F under the specified extreme-temperature testing procedure.

The FAMG must also safely accommodate the ammunition types identified by the solicitation, including linked 5.56x45mm ammunition and high-pressure 5.56mm ammunition originally made for the HICAR program. Additional requirements address safety during rough handling and drop testing, including preventing unintended bolt release or safety movement.

The solicitation further specifies that the weapon should not create a safety hazard if fired with an obstructed bore.

A Structured Development Process

The proposed acquisition process is divided into multiple stages as usual. The first is submitting a white paper describing the proposed solution, including estimated cost per weapon, a prototype delivery timeline, anticipated development risks, photographs, and how the design addresses the government’s technical requirements.

Selected companies will proceed to a virtual pitch day lasting no more than 30 minutes, including questions and answers. Successful participants can subsequently enter the Request for Prototype Proposal process.

The government also retains the ability to introduce companies with complementary capabilities to facilitate teaming arrangements. However, proposers are not required to accept such recommendations.

Ultimately, the FAMG solicitation seeks to push the light machine-gun category toward greater portability without abandoning the reliability and durability that special operations forces demand. Replacing the MK46 is therefore less about simply producing a lighter belt-fed weapon and more about balancing a demanding collection of requirements within a single system. The successful design must show that modern manufacturing and materials can deliver significant improvements in weight, recoil, reliability, durability, and integration while remaining mature enough for rigorous government testing.

The ZiD 6x49 proposed rifle. Photo credit: Unknown.

In 2015, photographs and videos began circulating of several prototype rifle designs from the mid-2010s, chambered for an obscure experimental round, the 6x49, which was the Soviet Union’s unified 6mm cartridge. The photos and videos show new developmental rifles chambered for the Soviet-era work resurfacing with some of the biggest Russian defense contractors. First publicly observed on 19 September 2015 during the Tsentr-2015 exercises in Donguz, Orenburg Oblast.

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Russian news coverage of past and present developments. Photo credit: Russian Channel 1.

The cartridge

The cartridge traces its origins to late Soviet development aimed at a high-velocity caliber to replace the 7.62x54 cartridge. It is designated the Unified 6mm program, explored in the 1980s, intended for both sniper/marksman roles and general-purpose machine guns. Ballistically, the 6x49 was designed to replace current calibers with a standard high-velocity cartridge, offering flatter trajectories and greater retained velocity/penetration at extended ranges than existing Soviet rounds. The Soviet 6x49 muzzle velocity is in the region of 3,608-3,772 fps; if accurate, it would place it in the same performance class as some modern high-velocity 6mm efforts elsewhere. Chatter on the new Russian 6x49 may indicate a lower muzzle velocity, reducing recoil and extending the service life of the barrel and weapon.

If the Soviet 6mm program had been a success, the PKM may have been rechambered or replaced. By Lynndon Schooler.

The Gun

The guns appeared in Russian media in 2015, the result of renewed interest in alternative small-arms ballistic concepts worldwide during the mid-2010s; several states were trialing new 6mm designs, and Russia’s ongoing small-arms modernization led to the re-examination of an older experimental project. In Russia’s case, the story of the 6x49 began in the mid-1980s, ended in the late 1990s, and resurfaced in the mid-2010s, partly because of earlier domestic projects for newer ballistic solutions. Scattered prototype photos, with speculation that a new-old Russian round was being re-evaluated. At the time, IzhMash presented the A-6 “Assault Rifle” modernized on the AK platform, and ZiD presented an unnamed new design.

Soviet 6mm experimental machine guns in Tula. By Lynndon Schooler.

What we actually saw, most of what circulated in 2015-2016, was either single demonstrator guns or conceptual mock-ups rather than finished designs. It is important to emphasize that the official 6x49 assault rifle program was part of a research and development program; some chatter shows the program may have been canceled in 2015 or put on hold.

The 6x49 idea is reported to improve long-range performance, greater supersonic range, and better armor and barrier penetration than the 5.45x39 and 7.62x54, all of which are attractive for marksman rifles and machine-gun roles. The trade-offs include reduced magazine capacity and loadouts, increased weight, increased barrel wear from high velocities, and logistical complexity in fielding a new caliber. Historically, the collapse of the USSR and the cost of retooling meant that many promising cartridge projects were shelved; that institutional headwind persisted even when the technical case was revisited in the 2010s.

Why didn’t it replace existing calibers on its second go around? Timing and several practical realities explain why the 6x49, despite its bold ballistic claims, did not replace existing calibers on its second go-around. First, timing: there was no urgent need at the time, since Russia typically reacts to events rather than acting proactively. Second: adopting a new standard cartridge across an army requires long-term procurement, logistics, and industrial investment; third, modern doctrine increasingly favors capacity; fourth, incremental improvements to existing rounds (new projectile designs, improved propellants) can achieve many benefits without a wholesale caliber change. While 6x49-style ballistics are attractive on paper, the organizational costs of adoption are substantial for any nation to adopt a new caliber.

2015 IzhMash A6 6x49 “assault rifle.” Photo credit: Unknown.

The renewed attention to 6x49 in 2015 reveals how legacy Soviet research and development can resurface, now as the U.S. has introduced the 6.8x51 cartridge. It reflects the global trend toward larger, high-velocity calibers, which influences thinking across multiple countries. Whether Russia will ever field a 6x49 service round remains uncertain. Still, the experiments remind us that the search for an optimal balance among range, lethality, weight, capacity, and logistics is ongoing, and that sometimes the most interesting stories in small arms are as much about industrial and institutional choices as they are about pure ballistics.

Conclusion

The 6x49 rifles that emerged around 2015 represent an interesting revival of late-Soviet ballistic concepts and notably predate the U.S. Next Generation Squad Weapon (NGSW) program. Russian work on 6mm cartridges appears to remain active, at least publicly, now focusing more on 6mm (6.02mm) intermediate-class ammunition rather than a full-power replacement. However, recent examples of weapons chambered for the legacy 5.45 caliber include the RPL-20 field test and the adoption of the AM-17. At the heart of these past efforts is a high-velocity 6x49mm cartridge that could, in theory, assume some roles if not all roles currently filled by the venerable 7.62x54mm and incrementally enhance Russia’s small-arms capabilities. Those potential gains, however, come with significant trade-offs in capacity, weight, cost, logistics, and force integration, making large-scale adoption uncertain at this point. For now, the 6x49 stands as a technically compelling but unresolved line of development.

This new program aims to bring new life to the 5.56 cartridge and carbine; perhaps this is a more logical path than the Army’s 6.8x51 approach. It offers a capability boost while preserving magazine and load-out capacity and improving ballistic performance.

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Vietnam produced the PKP and the STrL-P. By Lynndon Schooler.

I have previously covered the Russian PKP machine gun and its use in Armenia. Now, it is making an unlikely appearance in Vietnam. For decades, the backbone of Vietnam’s infantry firepower has been shaped by Soviet and later Russian weaponry. From Kalashnikov rifles to the PKM machine gun, Vietnamese soldiers have long relied on designs imported or licensed from abroad. But the landscape is changing. Vietnam’s growing defense industry, centered around the Z111 Factory, has begun producing locally manufactured small arms to reduce reliance on imports.

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Among the most significant of these new weapons is the STrL-P machine gun, a domestically produced copy of the Russian 6P41N PKP Pecheneg, a belt-fed general-purpose machine gun chambered in 7.62x54. It was unveiled for the first time at the Exhibition of 80 Years of National Achievements at the Vietnam Exposition Center in Hanoi on 28 August 2025.

The STrL-P represents Vietnam’s first attempt to develop an improved PKM design, having previously produced the PKM. By replicating the PKP Pecheneg, an evolution of the PKM, Vietnam signals both technological ambition and the desire for long-term autonomy in arms production. Reportedly, Vietnam requested a production license and technology transfer in 2019, which Russia reportedly denied. That may explain the minor changes visible on the displayed example. The model shown was produced in 2024 and bears serial number 5.

Why the PKP?

The Russian PKP Pecheneg, introduced in the early 2000s, refined the PKM by offering better sustained fire capability and improved barrel life. This was achieved through its distinctive enclosed-barrel design and an enhanced cooling system. For Vietnam, whose forces have relied heavily on PKMs, the Pecheneg represented a logical next step.

The PKP’s unique approach centered on reducing the combined weight of a gun plus two spare barrels while enhancing barrel performance. Its design merged two barrels into one and was supported by a dual cooling system. According to Russian patents, the PKP was intended to weigh 2.6-3.3 lbs. (1.2-1.5 kg) less than a standard PKM equipped with a spare barrel. A PKM with a spare barrel weighs 21.8 lbs. (9.8 kg), while the PKP came in at just 19.18 lbs. (8.7 kg). The tradeoff was that the PKP’s barrel was not designed to be replaced when hot, but it offered much greater endurance in return.

Dual cooling system of the STrL-P barrel. Note the wrong display information plaque for the locally produced RPD. By Lynndon Schooler.

Heavy reliance on Russian imports, however, poses obvious risks. Vietnam’s experiences in the First Indochina War, and even more so during the later Vietnam War, revealed just how fragile external supply lines could become in prolonged conflict or under shifting geopolitical conditions. These lessons instilled a lasting emphasis on self-reliance. By reproducing and adapting the PKP domestically, Vietnam can modernize its arsenal while insulating itself from the kinds of supply disruptions and political constraints that once hampered its war efforts.

STrL-P selector marking in the fire position. By Lynndon Schooler.

Design

Official specifications remain limited, but seeing it at the exposition shows that the STrL-P closely follows the PKP Pecheneg’s blueprint. The weapon is chambered in locally produced 7.62x54, the same cartridge used in the PKM, the Dragunov SVD, and other legacy systems still in Vietnamese service. This ensures compatibility with existing ammunition stockpiles, making logistics seamless.

Like its Russian counterpart, the STrL-P incorporates a heavy barrel with a dual cooling system, ensuring sustained accuracy, durability, and service life. Unlike the PKM, which required spare barrels for quick changes in the field, the Pecheneg design uses a single barrel that can sustain prolonged fire without overheating.

While there is no official data on the barrel material, the Russian PKP uses specialty steel derived from aircraft cannon barrels. The most distinctive feature is its cooling system:

· Rear section: passive cooling, pulling air under the barrel shroud across a ribbed barrel section.

· Forward section: active cooling, requiring the weapon to fire to pull air through vent holes in the gas block, channeling it under the barrel jacket toward the muzzle device.

Additionally, the PKP design features a tighter barrel-to-trunnion interface, reducing play and slop to decrease dispersion. This is said to increase accuracy by 1.6-2.5 times.

The STrL-P muzzle device is noticeably longer than on the original Russian PKP. Lynndon Schooler.

Which Role?

Machine guns are key features of all infantry movement. While rifles provide individual fire, the machine gun delivers the suppressive firepower that shapes maneuver. With a doctrine emphasizing mobility and adaptability across dense jungles, mountains, and urban terrain, Vietnam needs a reliable, versatile general-purpose machine gun.

The STrL-P may be intended to replace PKMs still in service or to be used with specialized units. At present, its exact role remains unclear. What is clear is that it offers greater durability and better sustained fire capability than legacy systems.

Feed tray cover with factory markings. By Lynndon Schooler.

Strategic Significance

The debut of the STrL-P fits into the broader trajectory of Vietnam’s defense ambitions. Over the past few decades, the country has expanded its domestic arms industry. Z111 Factory, long tasked with maintaining and upgrading imported arms, now produces both licensed and indigenous copies. From the STV family of assault rifles, the licensed production of the IWI 7.62x39 Galil and 5.56 NATO Negev LMG, Vietnam has been steadily diversifying.

The STrL-P extends this modernization to general-purpose machine guns, complementing Vietnam’s domestically produced PKMs. The core receiver design remains familiar, but the upgrades, focused primarily on the barrel assembly, reflect the PKP influence. Notably, the STrL-P lacks the oval cutout on the forward receiver seen on Russian PKPs, which were originally intended to reduce trunnion heating by eliminating the insulating receiver around the chamber area.

STrL-P receiver with no oval cut-outs. Also note the two plastic inserts inside the carrying handles, most likely indicating that the system is still in development. By Lynndon Schooler.

Potential Deployment

The STrL-P has yet to enter widespread service, but its unveiling at the expo suggests it is entering testing or limited frontline deployment. The People’s Army of Vietnam has long sought to modernize its small arms, and this new machine gun will likely see initial use with elite formations before regular infantry.

Chambered in 7.62x54, the STrL-P fits in layered firepower. Lighter weapons like the STrL-7.62 in 7.62x39mm or RPD derivatives provide mobile suppressive fire at short ranges, while the STrL-P delivers heavier, long-range automatic fire. Together, these form a balanced system supported entirely by domestically stocked ammunition.

Conclusion

The debut of the STrL-P machine gun came as a surprise. Vietnam’s program essentially reverse-engineered the PKP’s barrel assembly and adapted it to their domestically produced PKM. While there are design differences, the result addresses a key capability gap and provides significant firepower. Notably, most nations operating PKMs do not practice regular barrel changes, making this upgrade all the more practical.

One curious choice was to retain the side rail optics mount rather than add an M1913 rail to the feed tray cover, which would have been a more modern option. Even so, the achievement is striking. The STrL-P shows Vietnam’s resilience and self-reliance, showing that the country is no longer merely an importer of foreign weapons and designs but a producer of world-class infantry weapons in its own right.

Cracked M240L. Photo credit: Anonymous.

The FN MAG-derived M240 entered U.S. service in 1977 as a coaxial machine gun for the Abrams program. Infantry variants followed later, with the M240G adopted by the U.S. Marine Corps in 1991 and the M240B adopted by the Army in 1995. As capable as the weapon was, one common complaint followed it everywhere, its weight. For a machine gun carried by dismounted troops, every pound mattered.

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Cracked M240L receiver. Photo credit: Anonymous.

Lightweight program

That concern eventually pushed the Army toward a lighter medium machine-gun/general-purpose machine-gun effort that would preserve the M240’s reliability and combat performance while reducing the burden on the soldier. Around 2000, the Army began discussing weight reduction with FN Herstal. Those efforts evolved into the M240E6 development program around 2005. The goal was straightforward: use high-performance, lightweight materials and improved manufacturing methods to remove several pounds from the system without compromising the MAG’s proven design.

Photo of the failed buffer, note the buffer stop mark, short buffer plunger, and mark below the plunger, all indicators of a failed buffer assembly which failed internally or unthreaded and backed out. Photo credit: anonymous.

The broader trend was not limited to the M240 program. At roughly the same time, several lighter-weapon initiatives were underway across the U.S. military. U.S. Special Operations Command adopted the MK48, a 7.62x51mm variant built around the M249 concept, as a lighter alternative in the same caliber class. Weighing roughly 18.5 lbs, it offered a more mobile option for special operations forces and was also used in Afghanistan as a theater-specific weapon, especially in demanding mountain terrain. The common theme across all of these programs was clear: the military wanted firepower that could move faster and reduce fatigue on the gunner, without sacrificing the endurance expected of a true support weapon.

Cracked M240L receiver. Photo credit: hayzu02

The Army and FN’s weight-reduction work on the M240 ultimately led to the M240L. Testing focused on titanium receivers and a barrel shortened by roughly four inches. The final result began fielding in early 2012, after contracts were awarded. Compared to the standard M240B, the M240L reduced weight from 27.6 lbs to 21.8 lbs, a reduction of 5.8 lds, or about 21%. On paper, that may seem modest, but in the hands of a soldier already carrying ammunition, armor, and other mission equipment, it is a significant reduction in load.

Cracked M240L receiver. Photo credit: subieroux.

That lighter weight matters most when the gun is being moved, mounted, and employed over long distances. For infantry units, especially those operating on foot, shaving several pounds from a machine gun can improve endurance, reduce fatigue, and make the weapon easier to handle in complex terrain. In practice, the M240L offered a more manageable version of the familiar M240B without sacrificing the firepower and reliability that made the FN MAG family successful in the first place.

New buffer assembly, no wear mark on the buffer stop. By Lynndon Schooler.

The Problem

Like most weight-reduction efforts, however, the M240L introduced a tradeoff. The lighter design demanded greater attention to maintenance and inspection. In theory, the system remained robust enough for its intended role, but in practice, a lighter receiver and tighter operating envelope leave less room for neglect. When maintenance is not performed correctly, or when worn components are allowed to remain in service too long, the consequences can appear sooner on the lighter titanium Lima than on the heavier steel-receiver M240B.

Wear marks on the buffer stop show the gradual progression. By Lynndon Schooler.

PS magazine publication. Photo credit: PS magazine.

PMSC per the TM. Photo credit: 23&P TM.

That is where discipline in preventive maintenance becomes critical. A M240L with the lighter titanium receiver still depends on the integrity of the recoil system, buffer assembly, and main spring to absorb and control operational stresses. When those parts wear out or are ignored, the receiver can end up absorbing stress it was never meant to carry on its own. The result is often accelerated wear components or other serviceability issues that could have been prevented with proper attention. This also applies to the M240B.

Failed M240L receiver, note the long buffer plunger. It also has an M240B FCG. Photo credit by: subieroux.

This does not mean the M240L is unreliable. It means the weapon has less tolerance for complacency. The M240B, with its steel receiver, offers a more forgiving margin when the system is not perfectly maintained, but it can develop a cracked receiver if not maintained, though it takes much longer to do so. The M240L, by contrast, rewards its gunner with a lighter weapon but punishes neglect more quickly. That makes maintenance training and awareness essential. Gunners, armorers, and maintainers all need to understand that the Lima still requires higher professional standards and, in some cases, even greater vigilance to remain fully mission-capable.

This is how the buffer assembly should look with a long buffer plunger. Photo credit: Chewmilkbits.

One Reported Issue

One thing to pay extra attention to is the buffer assembly. In many cases, the hydraulic buffer can unthread and back out over time, causing the bolt carrier to miss the buffer plunger entirely or only strike it lightly before contacting the rear of the receiver, which it was not designed to do on the Lima and Bravo. For a quick visual check, the buffer plunger should not appear unusually short. If it does, that usually means either the buffer has failed internally, or it has unthreaded and backed into the stock. The unthreading is due to a poor buffer design, which allows it to unthread.

Backed out the unthreaded hydraulic buffer, resulting in a short plunger. Photo credit: Chewmilkbits.

Cracked M240B receiver. Photo credit: Anonymous

Talking to FN

According to FN engineers, the M240L meets the same minimum service-life standard as the M240B, which is a minimum of 50,000 rounds. Some M240Ls have reportedly surpassed 200,000 rounds, and some M240Bs and original MAG 58s have endured millions of rounds with proper care. That kind of durability is not accidental. It is the product of sound design and disciplined maintenance over the life of the weapon.

Worn main spring, bunched up with many broken strands. By Lynndon Schooler.

Check your springs per the TM. Photo credit: 23&P TM.

The larger lesson is simple. The M240 series has long been valued for combining the proven reliability of the MAG design with the firepower needed for modern infantry combat. The move to the M240L shows how military small arms continue to evolve toward lighter systems that improve mobility without abandoning durability. But no amount of engineering eliminates the need for routine inspection, replacement of worn parts, and respect for the weapon’s operating limits.

Also, another note, both the M240B and M240L are not designed to be dryfired, which causes excessive wear on the bolt guide rails and, over time, leads to cracking and eventual failure.

Cracked M240L bolt guide rails. Photo credit: rawlandayotte

Photo credit: M240 Machine Gun: Dry Firing Can Crack the Receiver > 75th U.S. Army Reserve Innovation Command > Article View

Conclusion

In the end, the M240L was designed to meet the same standards as the M240B, maintaining its firepower while reducing overall weight. Still, that advantage comes with tradeoffs if the weapon is not properly maintained. Weight savings are valuable, but they only pay off when matched with proper training and disciplined maintenance. For a system like the M240L, that balance is what keeps it both lightweight and fully mission capable, even if it demands a bit more attention during PMCS to extend its service life.

Photo of the failed buffer, note the buffer stop mark, short backed in buffer plunger, and mark below the plunger, all indicators of a failed buffer that unthreaded and backed out or failed internally. Also note the cracked feed tray cover. Photo credit: subieroux

Screenshot from the released video. Video credit: super rembo.

Quick, reportedly light, and a little mysterious, the OTs-142 (original source designation) light machine gun has started circulating through Russian forums and Telegram accounts as the latest experimental entry in Tula’s long line of OTs projects.

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OTs is an abbreviation for “weapon of the Central Design and Research Bureau of Sporting and Hunting Arms”. Official information is unavailable and has been left to open-source releases, so we must decipher what they provided; the original source is from a Telegram account: https://t.me/super_rembo/9624.

What we can do is assemble the clearest picture available: the OTs-142 appears to be a compact, squad-level belt-fed support weapon in the same family of experiments that produced the OTs-124 and OTs-128 (the Alatau-family projects, which I covered earlier), where designers at TsKIB SOO and related Tula bureaus have been rethinking how to deliver automatic fire with modern ergonomics and unusual feed arrangements.

MTs-566. By Lynndon Schooler.

These systems were based on the MTs-566 semiautomatic designated marksmen rifle. The OTs line is known for unconventional solutions, bottom feeding, proprietary link designs, and ammo boxes that do more than carry ammunition, and the OTs-142 seems to follow that lineage. So essentially, the 5.45x39 OTs-142 is a smaller version of the .308 OTs-124. However, it fills the squad’s automatic weapon role.

Previous Russian patent on the concept that the OTs-142 follows. Photo credit: Google Parents.

The Gun

Unlike traditional light machine guns, the new OTs-142 prioritizes fast reloads and capacity through its micro-caliber legacy chambering. Based on the Alatau program’s visible prototypes, the emphasis is on uninterrupted 12 o’clock M1913 rail for optics and enablers. Most important is the unique feed system designed to keep the gunner firing by quickly getting the gun back in action, rather than breaking contact for lengthy reloads, thereby reducing reload times for gunners under stress.

The OTs-142 is chambered in 5.45x39mm, its weight has not been released yet, and it can sport 13, 16.3, and 20.5-inch (330, 415, and 520mm) barrels to fit different mission sets for a belt-fed weapon, and is said to be lighter than the RPK-74 and RPL-21. If accurate, they indicate a weapon is intended for a squad automatic weapon role where the volume of fire to provide suppression is required to help enable maneuver. The chambering provides capacity and enables the LMG to suppress and support operations for longer, though with a reduced effective range compared to a GPMG.

The U.S. M249 SAW has a conventional layout. By Lynndon Schooler.

From the Alatau relatives (OTs-124/128), we can infer several likely features: bottom or otherwise unconventional feed geometry that integrates the ammo box with part of the feed mechanism, including the feed ramp, feed paws, and cartridge guides, with the first cartridge presented on the feed ramp. This concept turns the ammunition box into a large box magazine, in which the magazine is inserted, and the weapon is racked to chamber a cartridge. The Alatau designs also explored using the ammo box as part of the feed/cover arrangement rather than a feed tray and feed tray cover, a design choice that trades some complexity for a slimmer receiver profile and faster reloads.

One feature of this new concept is that the metallic, non-disintegrating empty belt returns to the soft ammo box when the weapon fires. This eliminates an empty belt hanging out of the gun. Retaining the belt makes it easy to reuse, though it could lead to issues when feeding a loaded belt and getting caught on the empty section as it comes back into the ammunition pouch.

The available video shows the gun firing from the open bolt using a reciprocating charging handle and ejecting from the right side of the gun. The weapon’s operating system matches the earlier patent RU2767387C1, which uses a PK-type feed arm assembly on the left side of the receiver to feed the belt into the gun.

Tactical intent and where OTs-142 might fit

The OTs-142 offers squads a higher-volume, more controllable automatic option that prioritizes quick reloads to get the gun back in the fight, primarily during an assault. As Russian machine gun trends move towards more assault machine guns, a 5.45-based LMG would offer ammo compatibility (though it uses proprietary belts) with standard assault rifles and lighter ammunition for increased available volume of suppression. The concept would give assault teams an advantage in suppressing objectives and quickly reloading to keep guns up, suppressing an objective as they maneuver to take the objective. So there is merit to the concept.

Bolt and feed assembly. Photo credit: Google Parents.

Two reasons drive interest. First, the OTs series represents an unusual design among Russian engineers: bold departures from classic feed-tray machine-gun layout and an emphasis on quick reload speed. Second, there is the real estate of optics and enablers. Even if the OTs-142 remains a niche prototype, the concepts evolved from thinking about blending the volume of fire and modularity.

Magazine ammo can. Photo credit: Google Parents.

The OTs-142 is the result of the Alatau experimental machine guns. This program saw little publicly released information, so I went off available photos and the one publicly released video of the OTs-142. As usual with TsKIB SOO projects, the most reliable picture will arrive only if and when the bureau or state procurement channels publish formal specs or images. Until then, the OTs-142 remains a promising hint of where Russian small arms may be headed, not a finalized operational system.

Feed system. Photo credit: Google Parents.

Conclusion

The OTs-124/142 are a unique development, though not without their cons. The ammunition box is the weak link, with part of the feed assembly on the ammunition can/soft pouch. This can lead to easy damage in a realistic combat environment. On the upside, it speeds up reloads, keeping the gun up. However, the system does not prioritize quick barrel changes from the information we have, as Russian doctrine and practice show. Once the cons are worked out and proven reliable, I see this concept as feasible. As more information is released, I’ll update this article.

RPL-21 is a similar bottom-feeder LMG concept. By Lynndon Schooler.

AO-22M experimental general-purpose machine gun. Photo credit: Rostec.

As the trend moves towards lighter and lighter machine guns, covering the AO-22M is a must, as it is one of the lightest 7.62x54 experimental machine guns. The AO-22M is one of the lesser-known Soviet experimental machine guns, and finding detailed information about it is challenging. Despite the limited data, its visible design features are quite intriguing.

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AO-22 experimental general-purpose machine gun. Photo by Lynndon Schooler.

The AO-22M was an experimental lightweight 7.62x54 general-purpose machine gun. One of the most notable aspects of the AO-22M is its weight of 13.62 lbs. (6.18 kg), making it approximately 3 lbs. lighter than the PKM. The AO-22M represents a further improvement over the earlier AO-22 model, with development beginning in 1962 by designers Gryazev and Lyubimov to address the AO-22’s shortcomings and significantly simplify the design.

AO-22 experimental general-purpose machine gun, note the upside-down push-through belt. Photo by Lynndon Schooler.

The AO-22M is said to have a rate of fire of 700 to 800 rounds per minute, reportedly slower than that of the AO-22. One of the key redesigns was the transition to a conventional gas-operated piston system, in contrast to the AO-22’s distinctive annular gas piston that encircles the barrel.

Rakov PKM belt loader and belt. Photo by Lynndon Schooler.

The AO-22M is a gas-operated, fully automatic weapon that operates using a long-stroke gas piston. The AO-22M is a belt-fed machine gun that reportedly employs a two-stage feed system, similar to that of the PK. Spent cartridges are ejected from the right side of the weapon and forward through the ejection port. The bolt is highly likely to have a plunger ejector. The bolt’s forward movement pushes the previously spent cartridge through the ejection port chute under the belt, feeding it into the weapon. The forward ejection was chosen because the receiver is shorter than the PKs. This design prevents spent casings from hitting the shooter and ensures that the right-side belt feed is not obstructed.

AO-22M at the Army Forum 2019 near Moscow. Photo by Lynndon Schooler.

The receiver is shaped to potentially eliminate bolt guide rails, which is another decision to reduce weight. The receiver is stamped steel with a riveted front and rear trunnion. The AO-22M possibly utilizes a PK or similar ammunition box and mounting interface design that can be attached beneath the receiver.

The barrel features a heavier profile with fluting located behind the gas block. This design enhances cooling efficiency while reducing weight by increasing the surface area exposed to air, allowing for more effective heat dissipation.

PKMs next to a PK on a Stepanov tripod. Photo by Lynndon Schooler.

The feed tray cover curve gives a futuristic soviet look, and the stock position would provide a good line of sight and check rest. The entire weapon has a streamlined design that could be optimized to minimize material use while also reducing gear snagging. The feed tray cover latch is on the right side. The rear sight is graduated to 1,400 meters and has no windage adjustment. Windage adjustment would be done on the front sight, like an AK, windage drum, and elevation sight post.

The tripod mounting points are designed for either a Samozhenkov or Stepanov tripod. Two forward-mounting lugs are located on the gas piston tube, and the trigger guard’s unique design serves as the rear tripod mount. This isn’t the best rear mounting solution, but it is enough to meet the requirement. In terms of performance, the Samozhenkov tripod offers better traverse and elevation mechanisms, though it is significantly heavier than the lightweight Stepanov tripod, which lacks them.

From what I can gather, the AO-22M uses a rotating multi-lug bolt that locks into the barrel extension, similar to the M249/ Minimi. This approach was taken to simplify the receiver’s manufacturing, eliminating the need for locking shoulders in the front trunnion and relying only on the barrel and bolt. The trunnion now locks the quick-change barrel into the weapon. Now, I would like to see the machine gun disassembled.

There are only right-side photos of the AO-22M. Photo credit unknown.

I have more questions than answers without the ability to disassemble and closely examine the AO-22M weapon or access additional photos. I am especially interested in reviewing the factory test results and any archival information related to the AO-22M.

The AO-22M is not a new concept, and it demonstrates that the requirements established in 1962 remain relevant today. The goal has consistently been to produce a lightweight, 7.62mm general-purpose machine gun that is easy to manufacture. Every effort has been made to simplify the design to reduce cost, weight, and enhance manufacturability. During the Cold War in the Soviet Union, cost and manufacturability were the most significant factors, while weight reduction was often a secondary concern. However, it was occasionally considered in Soviet weapons solicitations, such as the Kalashnikov PKM. It must be noted that the AO-22M is an experimental prototype and may have looked different if it had gone into serial production.

I fully support reducing the weight of weapons, as long as it doesn’t compromise their reliability, durability, or longevity. As I mentioned earlier, weight reduction benefits soldiers and lowers logistical costs. Another note on weight, during the 1960s and 1970s, both the Soviet Union and the United States tested polymer machine gun links to achieve further weight reduction, although this hasn’t garnered significant interest yet. Concerning the AO-22M, I hope to return to Russia someday to uncover more information. I will conclude here and continue with the machine gun chronicles.

First SAW program HK23A1. Source: dtic.mil

In 1957, the M14 rifle and M60 machine gun were adopted. The M14 program, which aimed to develop the M15 squad automatic rifle, was canceled in 1959. Later, the M14E2 was introduced as an interim solution to provide the infantry squads with a suitable solution. The United States Army Infantry School developed the M14E2 concept as a squad automatic weapon. This variant was issued in 1963, redesignated as M14A1 in 1966, and saw limited service during the Vietnam War. From the 1950s to the 1980s, there was no suitable replacement for the BAR (Browning Automatic Rifle), leaving infantry squads vulnerable and inadequate. During the Vietnam War, the M60 served as a company-level machine gun assigned to a platoon weapons squad.

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Near the end of the Vietnam War, the US Army initiated the Squad Automatic Weapon (SAW) Program in 1972. The goal was to provide infantry squads with a lightweight weapon capable of delivering a high volume of fire. Between 1972 and 1976, the 6mm SAW program was in operation. Initially, the SAW program aimed to evaluate both 5.56mm and 6mm weapon systems. Subsequently, all 5.56mm systems were removed from the 6mm SAW evaluation and designated solely for informational testing and reporting as an engineering design test. By 1976, the Army had lost interest in the 6mm caliber and shifted direction to a 5.56mm SAW.

6mm/ 5.56 SAW

The Armament Command requested testing of foreign 5.56mm machine gun designs to assess their potential for US military use. This request was made in response to the need to enhance the lethality of infantry squads. It’s important to note that every weapon undergoes various stages of development to evolve and refine its design; no weapon is perfect from its initial conceptualization. Before the U.S. Army’s 1974 test, Heckler & Koch developed a smaller 5.56mm version of their 7.62x51mm HK21 machine gun, which was named the HK23. The variant submitted for testing in 1974 was designated the HK23A1.

HK23A1. Source: dtic.mil

Two weapons were procured for this evaluation: the HK23A1 and the FN Minimi. The HK23A1 was tested at Aberdeen Proving Ground in Maryland, while the FN Minimi was evaluated at the US Army Infantry Board in Fort Benning, Georgia.

The HK23A1, manufactured by Heckler & Koch of West Germany, is a lightweight, closed-bolt, roller delayed blowback, air-cooled, belt- or magazine-fed weapon. The selective fire mechanism allows for semiautomatic, fully automatic, and 5-round burst modes. The cyclic rate of fire is around 870-890 rpm.

The ammunition stated for the test included the 5.56mm M193 and M196 cartridges, the XM287 heavy ball, and the XM288 tracer. Three different barrel types were provided, each featuring a distinct twist rate in the rifling. The appropriate combinations of cartridge type, rifling twist rate, and locking-piece angle are essential for the proper operation of both belt-fed and magazine-fed weapon configurations.

The HK23A1 fired 2,400 rounds during testing, including inspections, accuracy tests, and maintenance evaluations. However, the endurance test was halted due to frequent feeding failures and safety concerns. Issues included severe case-head swelling and primer ejection. Testing in extreme temperatures was canceled, and the causes of malfunctions were not identified. The mean number of rounds between failures was not specified, but the malfunction rate was 72 per 1,000 rounds, with seven parts requiring replacement due to stoppages.

Broken stock. Source: dtic.mil

For the endurance test, firing was conducted in 200-round cycles following test guidelines. The weapon was cooled after each cycle and scheduled for cleaning, inspection, and relubrication after every 10 cycles. Weapon accuracy and dispersion, projectile velocity, and stability were to be checked at each maintenance interval. The cyclic rate of fire was recorded throughout testing when fired from the bipod.

Testing was terminated before the remaining 20 cycles were completed, which would have used a firing sequence similar to that shown for the first 10 cycles. Maintenance was scheduled to be performed after every ten 200-round cycles fired. The test results are presented in four tables.

A representative sample of cartridge-case casualties during firing showed swelling of the case head and expansion of the primer pocket, with 51 cases of swelling and 36 instances of blown primers. While these changes often indicate excessive pressures in the ammunition, the velocity and pressure data from the same lot do not support this as the cause. During controlled 5-round burst firings, the weapon’s burst controller often malfunctioned, and other weapon stoppages obscured the frequency of this issue. There were nine recorded 4-round bursts and 11 occurrences of 6-round bursts during malfunction-free firing attempts.

Analysis of the 1974 HK23A1 machine gun test was unreliable from a performance standpoint, although the shooter readily cleared most stoppages through immediate action.

The weapon largely failed due to reliability issues, though the Army states they weren’t ammunition-related. This was caused by the US Army’s replacement of ammunition from the previously mentioned M193 and M196 with XM287 and XM288. This new ammunition was incompatible with the HK23A1 machine gun. Because the cartridges had thinner walls, ruptures occurred, leading to significant operational problems and a negative assessment of the weapon tests’ outcomes. At the end of the report, the Army said the weapon design is satisfactory, though further refinement would enhance the weapon’s serviceability.

It does not specify, but this is likely the thin-wall XM287/XM288 ammunition. Source: dtic.mil

5.56 SAW

The second attempt was the 1978 5.56 SAW program, which involved the larger HK21A1 instead of the HK23A1 from the first test. The HK21A1 was configured for a 5.56x45mm cartridge and designated the XM262. Later, the HK21A1 would evolve into the HK21E.

Comparative testing began in 1979. The machine guns underwent 10 months of comprehensive testing under extreme weather conditions. They were exposed to desert sand, mud, and silt. The tests included the reliability of the weapon, the probability of hitting targets at distances of up to 1,000m, the ability to quickly replace the barrel within 10 seconds, safety, durability, interchangeability of parts, firing behavior, the ability to self-ignite a cartridge left in the chamber, ease of use, and other characteristics. In total, the samples underwent 54 different types of tests.

M249, set up with two long barrels and one short barrel. Photo by Lynndon Schooler.

In 1980, the SAW program concluded with a final report stating that none of the candidates fully met the evaluation criteria. However, the FN XM249 MINIMI light machine gun met most requirements. This led to the XM249 being adopted as the M249 by the US Army in 1984, and the US infantry finally had an adequate squad automatic weapon.

Roof top M249s. Photo by Lynndon Schooler.

Sources:

https://apps.dtic.mil/sti/pdfs/ADB000980.pdf

https://apps.dtic.mil/sti/tr/pdf/ADA094051.pdf

ZID Kord 5.45 light machine gun with short and long barrels fitted with a sound suppressor. The bottom barrel is a 6P69 barrel. Photo credit unknown.

In December 2010, the Russian Ministry of Internal Affairs initiated the Tokar research and development program, followed by Tokar-2 in 2016, to create a 5.45mm light assault machine gun. This initiative was likely influenced by the capture of IWI Negev light machine guns from the Georgian Army during the 2008 Russo-Georgian War. One of the primary requirements for the Tokar-2 was to integrate an alternate feed system that would utilize both a magazine and a belt. JSC “V.A. Degtyarev Plant” (ZID) developed the Kord 5.45 light machine gun.

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The Georgian Negev light machine gun was captured during the 2008 Russo-Georgian war. Photo credit unknown.

The original Tokar project requirements for the R&D program included variable rates of fire, approximately 550-650 rounds per minute in low and 900-1000 rounds per minute in high, quick-change short and long barrels, and a maximum empty weight of 14.5 lbs. (6.5 kg). The effective range was 800 meters, and the minimum barrel service life was 15,000 rounds.

Captured Georgian Negev identification tag. Photo credit unknown.

Original Tokar Kord 5.45 proposal. Photo credit unknown.

The Tokar R&D machine gun had its first patents filed in 2011, with the initial prototypes emerging in 2013. However, in 2016, the Ministry of Internal Affairs issued new requirements for a 5.45mm light machine gun, codenamed Tokar 2. These updated requirements reduced the selective rates of fire but introduced an alternative feed mechanism and a sound suppressor. The maximum empty weight requirement was also increased from 14.5 lbs. (6.5 kg) to 15.4 lbs. (7 kg). In 2017, ZiD presented the new Kord-5.45 light machine gun, built to the Tokar-2 requirements.

Kord 5.45 light machine gun. Note that the steel green ammo above the carrying handle features the mag well adaptor for mounting the ammunition box to the gun. Photo credit unknown.

The Russian Ministry of Defense has not expressed any interest in a 5.45mm machine gun, as the 7.62x54mm rifle cartridge is fundamentally superior to the 5.45x39mm machine gun cartridge in terms of effective firing range and kinetic energy. This makes it impractical to consider the 15.4 lbs. (7 kg) 5.45mm machine gun when there is a PKM machine gun at 16.5 lbs. (7.5 kg). However, if the program progresses further, the 5.45mm machine gun might still be an option for Russian law enforcement agencies such as the MVD and Rosgvardia National Guard. But now, this system could compete with the Kalashnikov Concern RPL-20 light machine gun.

PKM build. Photo by Lynndon Schooler.

The Gun

The Kord-5.45 Light Machine Gun is a long-stroke gas piston gun. It features a multi-lug rotating bolt for locking and fires fully automatic from an open bolt. Fully ambidextrous controls include the charging handle, which can be swapped from left to right.

The weapon has a quick barrel-change feature, with short and long barrels available. This is another new Russian trend to have configurable barrels instead of having two of the same barrels. This is not a big deal in this application, but this trend has gotten into some Russian military requirements. It is shown with very light-fluted profile barrels to meet the weight requirements. According to the 2011 patent, the bolt carrier assembly is very reminiscent of the IWI Negev bolt carrier assembly. This patent application was filed only one month after the MVD requested the Tokar project.

Patent image, RU 2458304 C1 “Automatic small arms with belt and magazine feeding of cartridges.”

The Kord-5.45 features a dual-feed system, allowing it to accept AK-74-compatible magazines. This includes the ZID 60-round double-stack magazines explicitly developed for the program; the weapon comes with six magazines. The machine gun uses non-disintegrating, connectable 50-round belt segments and feeds them with brass to the grass from left to right.

The belt box attaches to the magazine well and uses the magazine catch to secure the ammunition box. It can hold boxes of 100 or 250 rounds. The weapon features a nearly full-length feed-tray cover assembly, allowing for the mounting of various optics. Given the size of the feed tray cover, it is likely that most reloads are performed by pulling the belt starter tab through the gun to load the ammunition, and by opening the feed tray cover to the left to clear malfunctions.

Kord 5.45 light machine gun prototype. This is one of the few photos of the feed tray cover open.

A PKM machine gun. The Kord 5.45 LMG is only about 1 lbs. lighter than an empty .30-caliber PKM. Photo by Lynndon Schooler.

Thoughts and Conclusion

The necessity for a dual-feed light machine gun is debatable; while it offers unique features, it also adds complexity, cost, and weight for the user. A 5.45 light machine gun does not achieve the range and kinetic energy that a PKM provides, which should be regarded as the standard for a squad automatic weapon. However, the Kord 5.45 machine gun could benefit certain Russian law enforcement agencies, where overmatch is typically unnecessary. Currently, the system is limited to domestic sales in its existing configuration.

7.62x54 PKP. Photo by Lyndon Schooler.

The Kord 5.45 light machine gun represents a significant improvement over the RPK-74, particularly in sustained fire capability due to its higher ammunition capacity. It meets all the necessary contractual requirements effectively. However, considerations about the caliber may affect its overall appeal, especially given the established preference for the 7.62 caliber in squad automatic weapons, as demonstrated by the PKM. This preference emphasizes weight limitations, keeping the gun under 16.5 lbs. (7.5 kg). As a result, the Kord 5.45 will be mainly for domestic law enforcement, potentially limiting its future military interest. As of 2019, there has been no new information, but we look forward to further developments and additional publicly available information.

Quick notes on employing PKMs within an infantry platoon. This is primarily for those SOF operators training partner forces and those participating in multinational mission training partnerships. As all PK series barrels are interchangeable with the PK, PKT, PKM, and even the PKP, this improves the PKM’s modularity and sustained suppression capabilities.

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The Barrels

The different PK series barrels differ in mass, which directly affects sustained fire capability and employment roles within an infantry platoon. The PKT barrel weighs roughly 7.12 lbs. (3.23 kg), making it approximately 23.3% heavier than the PK barrel (5.78 lbs. / 2.62 kg) and 34.6% heavier than the PKM barrel (5.29 lbs. / 2.40 kg). Also, the PKT barrel is made from a much higher-grade steel than the PKM barrels.

This increased mass provides a substantially greater thermal sink. In sustained fire roles, particularly within a platoon weapons squad and tripod-mounted, the heavier PK and especially PKT barrels can absorb and dissipate more heat, delaying overheating and reducing the frequency of barrel changes. As a result, PK barrels could provide greater suppression capability because of their larger heat sink, enabled by their greater mass, with the PKT barrel offering the highest theoretical endurance under continuous fire conditions.

However, these advantages come with trade-offs. The PKT barrel, while the heaviest, lacks a front sight, so an optic is required. Additionally, the increased weight negatively impacts portability and handling, making it less suitable for maneuvering elements.

For general use within rifle squads, when the PKM is employed as a squad automatic weapon (SAW), it should retain its standard lightweight barrels. These provide a balance between mobility and firepower, enabling effective maneuver while still maintaining adequate sustained fire capability.

Additionally, heavier barrels (PK, PKT) favor sustained suppression and tripod-based employment, while lighter PKM barrels are better suited for mobile, SAW roles. Effective platoon-level employment could align barrel selection with mission requirements, balancing thermal performance against mobility constraints.

Ammunition

I always praised the PKM as an excellent GPMG, it does provide overmatch against most NATO-based 5.56 LMGs. But this comes at a cost: it’s larger and heavier ammunition, which limits how much partner forces can carry. The negative is the ability to provide and sustain suppressive fire to win firefights. This leads into the ammunition considerations, every squad member should carry an additional 100-200 linked belts, thereby increasing the GPMG’s ability to provide and sustain suppressive fire.

More PKM material to come.

The latest version of the PKZ. Photo credit: Design Bureau Perm Designers for Victory.

In June 2024, Izvestiya reported that a new experimental machine gun had been developed in Russia. This weapon is named the PKZ and was created in Perm at OOO Labi, the Design Bureau Perm Designers for Victory. The small company started out producing new ammunition cans for the PKM, which inspired him to develop a kit for the PKM, turning the GPMG into an assault machine gun. The PKZ is a significantly shorter version of the PKM, though I could not find any specific barrel length. It was noted that this machine gun was developed for use in the Russo-Ukrainian War.

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Decked out PKM. Photo by Lynndon Schooler.

Andrey Malkov, “Labi,” developed his concept based on the standard PKM and created a light assault machine gun. In April 2024, it was called the KPL Light Machine Gun Carbine (Карабин-Пулемет Легкий (КПЛ)). Around June 2024, it was changed to PKZ.

Short PKM. Photo by Lynndon Schooler.

The machine gun is advertised as weighing approximately 15.4 lbs. (7 kg); in comparison, a standard PKM weighs 16.5 lbs. (7.5 kg), which is about a 7% reduction in weight. The report also indicates that the PKZ is 3.30 lbs. (1.5 kg) lighter than the PKM machine gun, representing a 20% weight reduction. So one of these numbers may be slightly off. Depending on the stock, the weapon can be 33.5 inches (850 mm) or 31 inches (790 mm) long. A soft ammunition pouch with polymer-disintegrating links would further reduce the weight of the combat loadout.

The grip, stock, feed tray cover, and cheek rest are part of the upgrade kit. Photo credit: Design Bureau Perm Designers for Victory.

This is not a new weapon but a modernization of the PKM, converting the PKM into a short assault machine gun. This modernization starts with an upgrade kit consisting of a snub nose barrel, compact or sub-compact stock, and pistol grip assembly that covers the original trigger and is operated via a linkage to fire the weapon; this housing moves the trigger forward from its original location due to the short stock and moves the operator’s firing hand forward. Other accessories include the cheekpiece, bipod, and optics mounts. This kit attempts to replicate the layout of the M-60 machine gun, which is more of a quasi-bullpup design, thereby reducing the overall length.

There are different stock and pistol-grip options; note the top pistol-grip location. Photo credit: Design Bureau Perm Designers for Victory.

The weapon becomes more maneuverable with such a short barrel, however, the muzzle flash and concussion from the muzzle blast would be extremely intense for the operator. A suppressor would be necessary for this weapon for the operator’s comfort. This system would be suitable for mission sets that involve short spurts of fighting rather than prolonged engagements, but that’s something for special blurry-faced men. Compared to your grunt, which will fight for hours in certain situations, this could be a viable option once it matures for specialized units. But I don’t see your typical conscript rocking a snub-nose PKM.

This is the optimal PKZ setup with suppressed PKV. Photo credit: Design Bureau Perm Designers for Victory.

I have shot PKMs with chopped barrels with no issue. Still, the PKZ raises the question of whether reducing that short has any adverse effect on its reliability, or whether any adjustments are needed to the gas system for reliable operation under different atmospheric and environmental conditions. We have seen no publicly available live fire yet, only a mock-up of the weapon. However, in one interview, the designer notes that live-fire testing is conducted.

PKZ pistol grip assemblies. Photo credit: Design Bureau Perm Designers for Victory.

The Izvestiya article states that the PKZ is being tested, but the scale and organizations involved are unknown. As some of us know, the special forces PKP-SP has been in the works for over 10 years. However, some upgrades go faster, such as the multiple iterations of the AK-12 upgraded during the Russo-Ukrainian War.

PKZ pistol grip assembly. Photo credit: Design Bureau Perm Designers for Victory.

Thoughts

The PKZ’s reduced weight would enhance mobility and minimize fatigue, making the gun easier to manipulate and maneuver. However, there are trade-offs to consider. For example, a shorter barrel decreases both effective range and kinetic energy. On the positive side, these weapons are designed for close-quarters engagements, where limited range is less of a concern.

As the PKZ matures, I am interested in which organizations might adopt it. The concept is very interesting, so I would, of course, like to test one out myself. Until more information becomes available, I will leave it at that, but I will gladly provide updates once I learn more.

Spetsnaz PKM set up. Photo by Lynndon Schooler.

Zastava 7.62x51 M20 general-purpose machine gun. By Lynndon Schooler.

During my recent visit to the Zastava Arms factory in Kragujevac, Serbia, we had the opportunity to explore one of the region’s most renowned and historic manufacturers of firearms and artillery. With a legacy dating back to the 19th century, Zastava Arms remains a prominent name in the global defense industry.

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Our visit began with a warm welcome from the knowledgeable staff, who provided valuable insights into the company’s storied history, advanced production capabilities, and its ongoing role in both domestic and international military markets.

Following the introduction, we were given a comprehensive tour of the facility and an up-close look at Zastava’s full range of weaponry. This allowed us to closely examine the design, craftsmanship, and technical specifications of their products. A highlight of the visit was the live firing session, where we observed and participated in testing several firearms, an experience that revealed the performance and precision of Zastava’s engineering.

The repositioned feed position accommodates a push-through feed system. By Lynndon Schooler.

The New Gun

Unveiled at the PARTNER 2023 International Arms and Military Equipment Fair in Belgrade, Serbia, the M20 machine gun is a modified version of the M84, designed for the rimless 7.62x51 NATO cartridge. This modification necessitated a redesign of the feed system, enabling the NATO-standard M13 disintegrating-link belt to replace the original non-disintegrating belts used in the PKM series. This may be an effort by the Serbian Ministry of Defense to standardize on 7.62x51 for their machine guns, as it already relies on this caliber for its Designated Marksmen Rifles and precision rifles.

In changing the caliber from the rimmed 7.62x54 cartridge to the rimless 7.62x51 NATO round, a significant internal design change was required for the feed system, which uses the “push-through” M13 disintegrating link. The revised feeding arrangement developed for the M20 is pushed back on the receiver, allowing it to be used with the push-through M13 link. This is an interesting solution. Most nations that wanted a 7.62x51 and an M13 link for the PKM did not adopt them. Instead, they significantly lengthened the receiver, increasing its weight. This is a brilliant and original solution.

M20 modified bolt carrier and lateral cam roller. Lynndon Schooler.

Externally, the M20 features a modernized feed tray cover with an M1913 rail. It is worth noting that the rear sight is attached to one of their products for prototyping, most likely an M72. Another item to note is that it is said to change: the bipod, which appears to be from one of Zastava’s precision rifles, on the range, where we were informed it would be changed to a standard M84 bipod.

Comparison of the M20 and the M84M. By Lynndon Schooler.

The new feed system uses a modification of the original feed paw assembly, now mounted with a lateral cam roller, whose lateral movement drives the feed lever in the feed tray cover to actuate the feed paws to pull a belt into the weapon.

M20 feed tray assembly. By Lynndon Schooler.

For loading, an additional step is required. With the feed tray cover open, the cartridge guide on the feed tray must be lifted to place the belt under it. This is an added step, but it could be addressed by adjusting the design to curve the cartridge guide upward, so the shooter only needs to push the belt into the guides. Lastly, after shooting, one link remains under the cartridge guides; it can be easily pushed out with a new belt, but cannot be easily swept out by hand by simply sweeping the feed tray.

Showing the belt loaded under the cartridge guides. By Lynndon Schooler.

Key Features and Specifications:

· Caliber: 7.62x51 NATO

· Operation: Gas-operated, rotating bolt

· Feed System: Belt-fed, push-through with NATO M13 links

· Rate of Fire: Approximately 600-700 rounds per minute

· Weight: Approximately

· Barrel: Electro-chemical rifling (ECR), chrome-lined for extended service life

· Sights: Adjustable iron sights with provisions for optical mounts

· Mounting Options: Compatible with tripods and vehicle mounts

· Effective Ranges: Bipod: Point targets at 600 m; area targets at 800 m; Tripod: Point targets at 800 m; area targets at 1,100 m; Tripod: Suppression up to 1,500 m; maximum range 3,725 m

Performance and Operational Use

The Zastava M20 is relatively new to the market and is designed for versatility across the full spectrum of general-purpose machine guns. Its lightweight design is ideal for infantry units that require mobility without sacrificing firepower. The cold hammer-forged barrel ensures longevity and consistent accuracy, even during prolonged engagements. During our range trip, we were informed that the M20 they were shooting had fired nearly 30,000 rounds with only six malfunctions. This means on average, the weapon experienced one malfunction every 5,000 rounds fired. Not knowing whether this was ammunition-related, it would be difficult to calculate the Mean Rounds Between Stoppages (MRBS) or Mean Rounds Between Failures (MRBF), as ammunition failures do not count towards these metrics. This would be an interesting test to conduct alongside the standard M84 and collect the data.

The weapon’s gas-operated mechanism is engineered to function reliably in diverse environmental conditions, from arid deserts to humid jungles, and features a three-position regulator. Its compatibility with NATO-standard M13 belt links simplifies logistics for allied forces, facilitating easier integration into multinational operations.

While specific deployment details are limited, the Zastava M20 has been showcased at various defense exhibitions, indicating interest from both domestic and international military entities. We were informed at the time of writing that 15 M20 7.62x51 machine guns have been made for testing. The weapon we were shown was serial #00001. Its designation, “PM 7.62x51mm M20”, indicates that PM stands for Pešadijski Mitraljez, which translates to “infantry machine gun” or “light machine gun.”

M20 aluminum feed tray cover. By Lynndon Schooler.

For the soldier who carries and maneuvers with a weapon, the weight is the most important factor behind reliability. The 7.62x51 M20 weighs 22.04 lbs. (10 kg). The M20 weighs 2.64 lbs. (1.2 kg) more than the original 7.62x54 M84, making a 11.95% weight increase. For comparison, the Polish 7.62x51 UMK-2000 weighs 18.52 lbs. (8.4 kg), and the Bulgarian MG-M2 weighs 20.50 lbs. (9.3 kg). Weight is a significant consideration, especially for infantrymen and logistical costs.

Barrel life and receiver life are typically advertised at 15,000 and 25,000 rounds, respectively, standard figures across all PK/PKM manufacturers. However, during our visit, we were told the M20 had already surpassed 30,000 rounds. Given the heavier receiver and components inherited from the M84, I’d expect the actual receiver life to exceed the 25,000-round mark by a significant margin. It’s something I’d like to test and gather data on myself someday.

The M20 barrel uses the Electro-Chemical Rifling (ECR) process instead of cold hammer forging (CHF). This was done to improve mechanical properties, enhance accuracy, and reduce dispersion in a machine gun. The chrome lining is used to reduce corrosion and further enhance the barrel’s service life.

Conclusion

The Zastava M20 marks a significant advancement in Serbia’s small arms capabilities, blending traditional design elements with modern innovations. Its development demonstrates Zastava Arms’ commitment to producing reliable, adaptable weaponry that meets the evolving demands of contemporary warfare. As defense forces worldwide seek to standardize and modernize their arsenals, the M20 offers a compelling option for nations looking to enhance their machine-gun capabilities.

With its combination of reliability, adaptability, and compatibility with NATO standards, the Zastava M20 is poised to be a valuable asset in the arsenals of armed forces seeking a modern, versatile 7.62x51 machine gun solution.

Sources: Zastava Arms, https://www.zastava-arms.rs/en/home

Smoothbore SVDG and PKG. Photo Credit unknown.

During the Cold War, the Soviet Union sought out new ballistic solutions. This is one of these programs, it was built upon a series of studies and a research and development initiative focused on sub-caliber fin-stabilized discarding sabot (FSDS) flechette ammunition, which took place from 1960 to 1981. The motivation behind this research largely stemmed from the US Special Purpose Individual Weapon (SPIW) program, which ran from the 1950s to the 1970s.

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In the mid-1960s, engineers at NII-61, now known as TsNIITochMash, developed sub-caliber FSDS ammunition. This type of ammunition featured several notable characteristics, including low recoil impulse, lightweight design, high velocity, and a flat trajectory.

One of the machine guns designed to utilize this ammunition was the 6P6-10 PKG Kalashnikov Machine gun - smoothbore, as noted in “Combat Cartridges of Small Arms” by V.N. Dvoryaninov. The book mentions at least two PKGs in the testing. When using FSDS ammunition, the PKG machine gun exhibited a remarkable barrel life compared to traditional ammunition and achieved impressive accuracy. After firing 30,000 rounds, the barrel displayed no signs of wear. However, the experiment was ultimately halted due to an ammunition shortage.

Standard PK/S. Photo by Lynndon Schooler.

Additionally, the PKG was tested alongside another weapon against a chambered in the 6mm VSS 6x53mm. Testers reported that the 6mm machine guns were unreliable, and TsNIITochMash insisted on conducting comparative tests for the 10/4.5x54mm and 7.62x54mm cartridges.

Subsequent research and development aimed to create a machine gun system for 10/4.5x54mm cartridges. This new system is intended to double the hit probability compared to the Kalashnikov PKM general-purpose machine gun.

Standard PKM/S. Photo by Lynndon Schooler.

In the 1960s, the Izhevsk Machine-Building Plant developed smoothbore weapons for this new cartridge. During this time, several versions of the SVDG sniper rifles and PKG general-purpose machine guns were developed, but here we will focus on the machine gun. The plant’s documentation includes information on research and development projects focused on a general-purpose machine gun and a cartridge featuring sub-caliber FSDS alongside a sniper rifle designed for sub-caliber FSDS ammunition.

SVDG smoothbore FSDS sniper rifle. Photo by Lynndon Schooler.

The PKM machine gun was modified to accommodate new ammunition, reducing its weight from the standard PKM’s 16.5 lbs. (7.4 kg) to 13.2 lbs. (6 kg). This is a significant weight reduction for warfighters and logistics. Research indicated that sabots were lethal at distances of up to 15 meters, prompting the development of a muzzle device to crush the sabots and minimize the dangerous area of the sabot fragments’ scatter. However, the durability of these devices was found to be low. One of the prototype muzzle devices is visible on the SVDG sniper rifle.

PKP-SP, to demonstrate the two bipod positions seen on the original PKG. Photo credit unknown.

Using sabot ammunition improved the barrel service life, at least through testing of the PKG: 32,000 rounds by the end. This could eliminate the need for a spare barrel. The flechette had a flatter trajectory and significantly reduced drift with crosswinds. Recoil was reduced by 15% compared to 7.62x54mm. With a muzzle velocity of over 3280 fps (1000 m/s), the flechette had greater kinetic energy than the 7.62x54mm.

In testing conducted in 1973, the experimental machine-gun system demonstrated a significantly flatter trajectory than the standard system. When firing single shots, it exceeded the standard system’s hit probability by 1.6 to 8.7 times. Additionally, when firing bursts from a tripod, the experimental system achieved hit probabilities ranging from 2.47 to 12.6, up to 21.3 times higher than those of the standard system. The shooting took place at distances of 700, 900, and 1000 meters, despite the smoothbore machine gun exhibiting increased dispersion, averaging twice that of the standard PKM. During the test, as in every other machine gun test report I have read, moving the bipod to the muzzle reduces dispersion.

7.62x54 and 10/4.5x54mm FSDS. Photo credit unknown.

During testing from 1981 to 1982, one concern with the 10/4.5x54mm cartridge was discarding sabot scattering, which could be hazardous to friendly troops. As a result, the military found this unacceptable and recommended stopping work on the sub-caliber FSDS ammunition.

The conclusion of the report from 14 October 1983 stated: “The experimental 10/4.5x54mm cartridges, while providing practically the same damaging effect of bullets on live targets (at a range of 600m) as standard rifle cartridges, are significantly inferior to them in terms of accuracy of fire, and to a lesser extent in terms of the penetrating effect of bullets on thin metal barriers. Considering the futility of many years of efforts to ensure acceptable dispersion characteristics, it is advisable to stop work on studying the possibility of creating a rifle cartridge with an arrow-shaped bullet.”

10/4.5x54mm FSDS. Photo credit unknown.

At the same time, among the employees of TsNIITochMash, there was an opposite opinion regarding the cartridge’s indicators in terms of the accuracy of the fire and its penetrating effect. Another disadvantage of the cartridge was the high labor intensity of its manufacture. According to the KBAL report on technological assessment dated 02 March 1982, the cartridge is not technologically advanced and cannot be accepted for testing at the experimental design stage. During the testing of the Soviet FSDS ammunition, the Soviet Union spent over 30 million US dollars at the time, and many think the development and testing were not completed. The 10/4.5x54mm was produced from 1965 to 1981.

US M962 saboted light armor penetrator tracer (SLAP-T). Photo credit unknown.

In December 1983, research and development on the 10/4.5x54mm cartridge and its weapon system were completed. The focus was then switched to the 6mm program, primarily the 6x49mm. Though the West, mainly the US, uses sabot ammunition, Russia may reconsider revisiting the program for its benefits. If you would like more information or are interested in Soviet cartridges, I highly recommend getting the four-book series of “Combat Cartridges of Small Arms” by V.N. Dvoryaninov.

XM235 LMG linked belt of XM732 6x45mm ammunition.

Introduction

During the Cold War, the United States and the Soviet Union constantly monitored one another’s military research programs. Developments in small-arms technology were no exception, most recently with the 5.56 and the Soviet answer, the 5.45x39. Although direct documentary proof is limited, there are plausible reasons to suspect that American experimentation with 6mm rifle cartridges in the early 1970s may have influenced Soviet thinking when they launched their own 6mm cartridge program in the mid-1970s. The parallel, slightly staggered timing of these initiatives, along with the broader technological competition between the two superpowers, suggests at least an indirect relationship.

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The U.S. 1970s 6mm

In the United States, interest in small-caliber, high-velocity ammunition intensified after the adoption of the 5.56x45mm cartridge and the M16 rifle during the Vietnam War. While the 5.56mm round demonstrated many advantages, reduced recoil, lighter ammunition weight, and high velocity, U.S. researchers continued to explore whether other calibers might offer a better balance of lethality, range, and controllability. By 1972, this search had produced several experimental cartridges, including the 6x45mm, a steel-case cartridge developed by Frankford Arsenal.

The U.S. 6x45mm concept was attractive because it retained the logistical advantages of the 5.56mm cartridge while enabling a heavier projectile with a higher ballistic coefficient and improved terminal performance. A 6mm bullet could potentially offer improved retained energy and stability at longer ranges without the recoil and weight penalties associated with full-power rifle cartridges like the 7.62x51mm NATO. The 6mm SAW utilized a 105-grain (6.8 g) projectile with a muzzle velocity of 2450 feet per second (747 m/s), making the new machine gun capable of an effective range beyond 800 meters. One key requirement was that the 6mm projectile contain enough trace compound to be traced beyond 800 meters, a capability the 5.56mm round at the time could not achieve.

These ideas appeared in various U.S. military studies during the early 1970s, when analysts considered whether a mid-caliber cartridge might eventually replace the 5.56mm round or at least augment it. In 1976, the Army redirected SAW design efforts, halting development of the 6mm SAW cartridge and shifting focus to 5.56mm light machine gun designs.

The Soviets

Although the 6x45mm never became a standard U.S. military cartridge, the concept was part of a broader trend toward an optimal intermediate caliber that balanced the competing requirements of modern infantry combat. This type of research was closely watched by Soviet analysts and the intelligence apparatus. The Soviet Union maintained extensive intelligence and technical monitoring programs aimed at understanding Western military developments, particularly those related to small arms.

6mm VSS 6x53mm, fired 6mm VS6 6x57 and unfired 6mm VSV 6x49mm.

The Soviet decision to develop a 6mm cartridge was first finalized in 1975. The research and development program NV5-124-75 was initiated to find the optimal 6mm caliber for a new rifle cartridge. This effort began with a little-known round called the 6mm VSS (ВСС), a 6x53mm cartridge derived from the parent case of the 10/3.5mm VSL-1 flechette ammunition. The 6x53mm VSS fired an 84.8-grain (5.5-gram) projectile and was intended to explore the ballistic potential of a high-velocity 6mm round in future Soviet infantry weapons.

This cartridge emerged during a period when the Soviet Union was also experimenting with advanced infantry weapon concepts similar to those pursued in the United States. American programs such as the Special Purpose Individual Weapon (SPIW) attempted to dramatically increase infantry firepower through flechette ammunition and novel weapon designs. The Soviets conducted parallel investigations, including the development of flechette-firing systems such as the PKG (6P6-10), essentially a flechette-capable adaptation of the PKM machine gun.

Within this context, the 6x53mm VSS functioned as both a conventional projectile cartridge and part of a broader exploration of high-velocity small-caliber ammunition. The program remained in development from 1975 until around 1982, reflecting sustained Soviet interest in optimizing a mid-caliber round for future service rifles.

6x49mm groove and grooveless cartridge case.

In 1981, the cartridge was redesigned and evolved into a new round known as the 6mm VSZ/1/M (ВСЗ), the 6x49mm. This new cartridge was developed at TSNIITochMash, a government-owned research and manufacturing organization in Klimovsk near Moscow that specialized in small-arms and ammunition design. The 6x49mm offered extremely high muzzle velocity and was intended to provide superior long-range performance compared with the standard Soviet 7.62x54 cartridge, potentially replacing it for sniper rifles and general-purpose machine guns.

The Question

The similarity in timing between American 6mm experiments and the Soviet 6mm program raises an intriguing question: Did U.S. research and experimentation help inspire Soviet work in this area? While the Soviet 6x49mm was technically very different from the American 6x45mm, being a larger, higher-pressure cartridge designed for greater velocity, the underlying concept was strikingly similar. Both efforts reflected the belief that a 6mm projectile might represent an ideal compromise between small-caliber velocity and larger-caliber lethality, if executed appropriately.

Conclusion

Given the intense technological rivalry of the Cold War, it would be surprising if Soviet planners were unaware of American experimentation with intermediate calibers. Even if Soviet engineers ultimately pursued their own design philosophy, exposure to U.S. research may have reinforced the idea that 6mm represented a promising direction for future infantry cartridges.

Thus, while definitive proof of direct influence remains elusive, the broader pattern of parallel development suggests that American experimentation with cartridges such as the 6x45mm may have contributed, at least indirectly, to Soviet interest in developing their own high-performance 6mm rifle ammunition during the 1970s and early 1980s. Its development has resurfaced in the 2010s, though reportedly in a modified loading, most likely a response to the early interest in the US Army's Next Generation Squad Weapons (NGSW) program.

M60E1 at the Infantry Museum, Fort Benning, Ga. By Lynndon Schooler.

A lesser-known chapter in the development of the M60 was the M60E1, its first stepping stone. Developed as a prototype, the M60E1 represented an early attempt to correct many of the shortcomings of the original M60, which entered service in 1957, saw heavy use in Vietnam, and remained in U.S. military arsenals until its gradual retirement in the 1990s.

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M60D in Khe Sanh, Vietnam. By Lynndon Schooler.

When the United States adopted the M60 machine gun in the late 1950s, it represented a major step toward a modern general-purpose machine gun (GPMG). Lightweight for its class and time period, chambered in the new 7.62x51mm cartridge, it seemed like a success on paper. In reality and in combat, however, the M60’s promise was quickly undercut by a series of flaws that frustrated troops and plagued the weapon throughout its service life.

M60E1, note the gas cylinder, bipod, and carrying handle location.

To address these issues, engineers developed the M60E1 prototype. Though it never entered mass production, the E1 played an important role in shaping the weapon’s future and laid the groundwork for later, more successful designs such as the M60E3, M60E4, and M60E6.

M60 and M60E3. By Lynndon Schooler.

Undesired Features of the Original M60

The standard M60 became the iconic American machine gun of the Vietnam era, but its flaws were hard to ignore. Soldiers and Marines quickly identified several design problems of the M60 had several practical shortcomings: changing a hot barrel required an asbestos mitt, an awkward and hazardous procedure under combat stress; its bipod was mounted to the barrel, so barrel swaps left the weapon unsupported and forced crews to carry spare barrels with additional bipods and gas cylinders, adding unnecessary weight; the receiver and internal parts wore rapidly, pins and spring plates loosened and crews sometimes used lacing wire to hold the gas system together; and maintenance was delicate because the gas piston could be installed backwards, requiring careful, trained servicing. While the M60 was effective, these shortcomings left soldiers and Marines calling for improvements.

Captured U.S. M60 in Da Nang, Vietnam. They called it “Đại liên đuôi cá” (Fish-tailed heavy machine gun), due to the fish-like shape of the stock. By Lynndon Schooler.

Development of the M60E1

The M60E1 emerged as the first systematic attempt to correct these problems. It was a refinement project focused on making the M60 more user-friendly in combat. The key changes included moving the carrying handle from the trunnion to the barrel so a hot barrel could be swapped quickly and without a mitt; relocating the bipod from the barrel to the gas-cylinder assembly so the weapon remained supported during barrel changes (removing the need to carry extra bipods and gas cylinders with spare barrels); and reconfiguring the gas system so it tied directly into the trunnion and receiver instead of being attached to the barrel, simplifying maintenance and improving reliability. These upgrades collectively made the M60E1 far more practical and combat-effective than the standard model.

M60D in Da Nang, Vietnam. By Lynndon Schooler.

Despite its promise, the M60E1 was never adopted. The E1 remained experimental, with surviving examples, such as one displayed at the Infantry Museum at Fort Benning, Georgia, serving as reminders of what might have been.

M60 with the carrying handle attached to the trunnion. By Lynndon Schooler.

Influence on Later Variants

Though the M60E1 was never fielded, it strongly influenced future developments. Features such as the quick-change barrel with a carrying handle and the bipod mounted to the gas system were later incorporated into the M60E3 during the 1980s, and U.S. Navy SEALs and other allied forces used the improved M60E4/Mk 43 Mod 0.

In this way, the E1 acted as a bridge between the flawed original M60 and the more refined versions that followed. It demonstrated that the Army and Marine Corps recognized the weapon’s problems and were actively testing solutions, even if bureaucracy and war kept those fixes from reaching the field immediately.

M60E6. By Lynndon Schooler.

Conclusion

The M60E1 remains a little-known chapter in the story of American small arms, overshadowed by the widely issued M60 and the more refined variants that followed. Combat in Vietnam highlighted the gap between design theory and battlefield reality, and the E1 was the first serious attempt to close that gap. Another issue was that the M60 was never fielded in sufficient numbers to support the infantry during the Vietnam War. For context, during the Korean War, the infantry structure had already been adjusted to address the lack of a dedicated squad machine gun by authorizing an additional M1918 BAR per infantry squad. This increase was meant to compensate for the squad’s shortage of organic firepower, since U.S. infantry lacked a true light machine gun at the time.

Budget cuts and a lack of institutional momentum ensured that the M60E1 never moved beyond the prototype stage. Yet its innovations would live on, influencing the M60E3, M60E4, and later modifications.

Had it been adopted, the M60E1 would have eased many of the frustrations soldiers and Marines expressed about the gun and reshaped the reputation of the M60 itself. Instead, it remains an experiment, a reminder of the Army’s willingness to adapt, and a stepping stone toward the later models that finally delivered on much of its potential.

At a distance, the receiver markings alone can identify this as a GM-94, not an LPO-97 with graduated flip rear sights. Photo credit Lynndon Schooler.

In this article, we’ll discuss the history and design of the Russian GM-94 repeating hand-held grenade launcher. This pump-action launcher was designed by the KBP Instrument Design Bureau in Tula, which received a request from the Ministry of Internal Affairs for a grenade launcher designed for urban operations. They developed a multi-shot launcher that utilizes the newly designed VGM93 43x30mm grenades. These grenades are engineered to minimize blast effects in confined urban environments, reducing the risk of collateral damage to the operator and their team.

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GM-94 Photo credit Lynndon Schooler

The goal was to create a more accurate grenade launcher than the existing RG-6, identified by its GRAU designation 6G30. A reduced capacity was acceptable if the new grenade launcher offered improved precision.

The primary concern is the grenade itself; the traditional VOG-25 grenade does not meet operational requirements. The new design aims to reduce the fragmentation radius from 20 meters to below 10 meters. To achieve this, a thin plastic casing was used for the grenade, allowing for a limited lethal radius that can be as small as 3 meters, depending on the specific VGM93 grenade. This capability enables the operator to fire the weapon safely at near point-blank ranges.

History

The RMB-93 shotgun is the inspiration for the GM-93 layout. Photo credit unknown.

The design of the GM-94 is based on the RMB-93 Lynx shotgun. The design layout called for a movable barrel and a stationary tubular magazine. The concept was first introduced in 1993, called the GM-93, but it gained interest from the Russian army only in 1997.

GM-94 was submitted to government testing in 2001, and in 2002, the Russian Federation Ministry of Defense adopted the GM-94, designated as LPO-97 ‘light infantry flamethrower’ and the thermobaric grenade ammunition. The LPO-97 was adopted for the RF chemical troops RHBZ/RChBD. The LPO-97 is classified as a flamethrower, which the Russian army considers most hand-held thermobaric weapons to be ‘flame weapons,’ even though they are thermobaric munitions. Thermobaric munitions are not defined as incendiary weapons; they rely on a chemical reaction to generate a blast wave and negative pressure as the explosion consumes atmospheric oxygen. This extraordinary pressure can collapse structures and organs. Shortly after adopting the LPO-97, it was used by the FSB at the 2004 Beslan school siege.

Prototype GM-93, Photo credit unknown.

In 2003, KBP initiated a research and development project for the Ministry of Internal Affairs. This project resulted in modifications to the weapon system to meet the customer’s specifications. After these adjustments, the GM-94 was officially adopted in 2005 by the Ministry of Internal Affairs, following the Russian Federation’s authorization of the weapon system and grenades for use by internal affairs agencies. The adoption was followed by the Federal Security Service (FSB) in 2008, the Federal Protection Service (FSO) in 2011, and the Russian National Guard in 2017, underscoring the widespread acceptance and use of the GM-94 in various security and defense agencies. In 2013, the GM-94 was used for avalanche control in accordance with RD 52.37.790-2013. This was first tested in 2009 as a portable means of avalanche control.

Prototype PLO-97 light infantry flamethrower. Photo credit unknown.

Design

The GM-94 was designed as a multi-shot launcher, and the pump-action design was chosen for its reliability and ease of use, similar to the US China Lake multi-shot pump-action grenade launcher used during the Vietnam War with the US Navy Seals.

GM-94 with the beech open. Photo credit Lynndon Schooler

The GM-94, based on the RMB-93 Lynx shotgun, is a pump-action, magazine-fed shotgun with an integrated tubular magazine located above the rifled barrel. The magazine holds three rounds and can be reloaded through a top-opening loading door above the receiver, allowing the operator to have three rounds plus one in the chamber. Fired cartridge cases are ejected downwards, enabling the GM-94 to be fired from either shoulder. The GM-94 trigger is a double-action-only, internal-hammer design that provides a reliable and consistent firing mechanism. An ambidextrous manual safety is above the pistol grip for ease of use. The folding stock folds over the receiver and serves as a carrying handle when folded, providing a compact, portable design. The GM-94 and the LP0-97 differ only slightly, and the rear sight can aid visual identification. The PLO-97 and early GM-94s use a flip sight for different ranges, and the current production GM-94s use a ladder sight from 50 to 300 meters. The GM-94 ladder sight has changed from a rounded loop to a rectangular rear ladder sight.

Prototype LPO-97 with VGM93 plastic-cased ammunition. Photo Caption Unknown.

Specs:

· Caliber 43x30mm

· Weight 10.6 lbs. (4.8kg)

· Capacity shots: 3 +1 in the chamber

· Muzzle velocity 280fps (85m/s)

· Effective range of 300 meters

· Maximum range 800 meters

Ammunition

The VGM93 43x30 grenade currently offers 11 filler types to meet various requirements. The most common are the VGM93.900 high-explosive fragmentation grenade and the VGM93.100 thermobaric. Non-lethal grenades include the VGM93.300 smoke, VGM93.200 tear gas, and VGM93.600 rubber slug. Depending on the charge, the grenade’s radius can be up to 3 meters, and the minimum safe shooting distance is only 5 meters.

Conclusion

The latest development of the U.S. M32A1 allows it to use the new 40x51mm medium-velocity ammunition, extending its range to 800 meters. The GM-94 could serve as a comparable alternative, with a range of 800 meters, already exceeding the traditional Russian GP series, which has a range of 400 meters. One GM-94 per squad would significantly increase the unit’s firepower. Introducing a multi-shot grenade launcher concept into Russian infantry squads could provide advantages similar to the USMC M32A1.

Mock-up of the proposed system and a GPR-20 disposable underbarrel rocket launcher.

Introduction

From the Soviet days to the Russian Federation, there have been numerous efforts to enhance hit probability through mechanical improvements and advancements in ballistics. A key innovation is an electronic automated control system. In January 2025, Russia patented an electronic, automated fire-control system for small arms, filed by Kalashnikov Concern. A mock-up of this concept was first publicly showcased in 2023. This automated control system is designed for the AK-12 and the future GPR-20 under-barrel rocket launcher. This may be a development to counter the new US Army’s new Vortex Optics XM-157 Next Generation Squad Weapon-Fire Control (NGSW-FC) or, more ambitiously, the XM29 Objective Individual Combat Weapon (OICW).

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The latest Russian smart scope system features a hybrid electronic automated fire control system that combines advanced technologies to reduce human error and enhance weapon precision and soldier lethality. This smart scope integrates a digital display, a laser rangefinder, thermal imaging, image recognition, a ballistics calculator, atmospheric sensors, and a compass. It adjusts the ballistics profile based on current atmospheric conditions to improve the likelihood of hitting a target on the first shot. This definitely sounds like a development influenced by the XM157.

In 2023, Russian news TV ZVEZDA released this glimpse of the proposed future system.

This new optic enables soldiers to engage targets quickly and accurately at a distance, eliminating or reducing the skill and human error involved in aiming and firing. The idea behind this system is that it can instantly transform every soldier into an expert marksman, without the need for difficult, expensive, and time-consuming additional training, which most armies struggle to provide. This approach seems practical, especially for a conscript army, at least on paper.

The system

The hybrid electronic automated fire control system is equipped with a rangefinder, image recognition, digital display, and thermal imaging, all interconnected through a communication interface. Its design includes an optical device with sensors allowing for automated firing based on sight signals. The patent does not specify the sight’s magnification.

Proposed system design. Notes that the weapon is likely heavy at the rear because the battery pack is located in the stock when a disposable GPR-20 munition is not mounted to balance the weight.

This sighting system is designed for the AK-12 assault rifle and GPR-20 under-barrel rocket launcher and offers automated firing options for both. The rangefinder includes a ballistic calculator, an information display, atmospheric sensors, and a system for determining the weapon’s position. The weapon’s location is established by determining its position relative to the target using an inclinometer, an electronic gyroscope, an accelerometer, or a magnetometer.

The image recognition module comes with an integrated information display. The trigger mechanism is an electric drive, while the power supply module includes a control system. The image recognition module identifies targets using data from the rangefinder and imaging modules, then marks the target area on the display. Users can adjust firing modes, including fuse selection and automated and manual modes, indicating compatibility with future programmable GRP-20 grenades. AK rifles aren’t known for their triggers, but this may make it more interesting, as the system tracks the trigger’s position.

The hybrid component is the electronically actuated trigger, which monitors the trigger’s position and facilitates automated firing via a signal from the sight.

The calculations demonstrate that the automated firing mode enhances shooting effectiveness by minimizing or eliminating errors and facilitating automatic target recognition and firing procedures. “As a result, the likelihood of hitting the target with the first shot at a range of 300 meters increases by 1.6 times for head targets and 1.4 times for chest targets.”

View from the optic, translated to English.

The system includes a 5-minute internal battery backup, with the primary battery located in the rifle stock; the runtime is not specified. The fire control system is designed to allow modules to be added or removed. With additional communication interfaces, the scope can be updated to newer software and kept up to date with the latest evolving threats.

The smart system component is translated into English.

The patent describes a soldier equipped with a display but doesn’t provide specific details. This display could range from a simple chest-mounted unit to a helmet-mounted one, similar to the U.S. Army’s Integrated Visual Augmentation System. Such a setup would enable Russian soldiers to use a helmet-mounted system to see through the scope without directly looking through the optic. By integrating this technology, soldiers could fire their weapons behind cover while positioning them around obstacles. This time, actually seeing what they are shooting at.

Conclusion

Implementing a hybrid automated fire system can significantly enhance weapon accuracy and soldier effectiveness on the battlefield. These technologies improve target acquisition speed, increase accuracy through precise measurements, enhance situational awareness, and reduce cognitive load during engagements. Collectively, they represent a substantial shift in Russian military doctrine and technology.

The Russo-Ukrainian War has accelerated the transfer of battlefield technology within Russia, helping close the technological gap in the future. Given its global implications, the question arises: will all components be of Russian origin, or will foreign processors and electronic subcomponents be used? This consideration leads to potential supply shortages and increased reliance on foreign suppliers.

Lastly, what scale will this sighting system be developed for? It is likely intended for the future “Ratnik” program. While technology can enhance capabilities, it cannot replace the need for proper training, which applies to all military forces. To improve soldiers’ shooting skills, it is essential to return to the basics and first master the fundamentals before incorporating advanced technologies. This is particularly important because technology can fail or underperform, as it often does in the military, necessitating a return to basic skills. This is where the XM157 features an etched reticle designed for use if the system malfunctions. This technology could significantly enhance their combat effectiveness if the Russian smart scope is deployed at scale. However, we must wait for further information on its development, and I will follow up as it progresses.

Nikitin TKB-521 General Purpose Machine Gun at the Tula Arms Museum from 2015. Photo by Lynndon Schooler.

The Russo-Ukrainian War has unearthed another unique piece of history, particularly in the context of Soviet machine gun development. As reported by ANNA-NEWS on February 25, 2025, Russia has captured a Soviet experimental Nikitin machine gun from an arms depot belonging to the Ukrainian Armed Forces.

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One notable observation about the captured weapon is that the charging handle is missing; it was designed as a separate, removable component that may have broken off, lost, or been installed incorrectly. Another essential point is belt compatibility: the Nikitin machine gun uses a proprietary push-through belt that differs from those of previous Soviet machine guns and is not compatible with PK belts.

Tula Arms Museum has at least one TKB-521 on display. Photo by Lynndon Schooler.

This machine gun was developed between 1955 and 1956 by Grigory Ivanovich Nikitin and Yuri Sokolov as part of a competition to develop the Soviet Union’s first general-purpose machine gun (GPMG). However, during the final stage of the competition, Mikhail Kalashnikov’s design team was invited to participate in an effort to speed up the Nikitin design team, and ultimately, the PK machine gun was selected for adoption in 1961. A pilot batch of Nikitin machine guns was manufactured and tested in different regions of the Soviet Union during troop trials. After the PK was chosen, the remaining Nikitin guns were sent to museums and into storage across the former USSR, including some in Ukraine. Following the collapse of the USSR, these machine guns remained in storage until one was recently discovered during the war.

Reported recovered Nikitin TKB-521. Photo credit ANNA-NEWS.

The History of the Gun

As warfare technology advanced, nations recognized the need to enhance their infantry capabilities, ultimately leading to the development of machine guns. Hiram Maxim’s innovative design, created in 1884, marked the advent of the first successful machine gun, demonstrating its effectiveness during the Russo-Japanese War of 1904-1905. In the context of World War I, militaries adapted their strategies and methodologies to integrate machine guns into combat operations effectively.

Machine gun development continued during the interwar period as preparations for World War II began. Germany adopted the MG-34 universal machine gun and later produced the simplified MG-42.

TKB-521 tank version. Photo credit unknown.

In the mid-1940s and 1950s, after thoroughly analyzing World War II’s combat experiences, many countries began developing technical requirements for new machine gun concepts. The armies of most nations adopted the German idea of a universal machine gun or general-purpose machine gun.

Nikitin TBK-521 General Purpose Machine Gun. Photo credit unknown.

The Soviet Union began developing a general-purpose machine gun after thoroughly studying German machine guns, which they found appealing. By 1946, the Soviet Union issued the first requirements for a new machine gun. In 1955, updated requirements were finalized for a machine gun chambered for the 7.62x54mm cartridge that could be equipped with an integral bipod, tripod, or vehicle mount and new weight requirements of 19.8 lbs. to 28 lbs. (9-13 kg).

The only disassembled TKB-521 image I could find. Photo credit: Modern Firearms.

Grigory Ivanovich Nikitin at the Tula Design Bureau developed a prototype machine gun from 1955 to 1956, designated with the factory index TKB-521.

The machine gun was gas-operated, air-cooled, and belt-fed. It featured a quick-detachable barrel and a milled receiver. It used a rotating bolt locking system, a push-through feeding system, and a self-regulating gas system, similar to the concept in the U.S. M-60 that was developed during the same period.

Reported recovered Nikitin TKB-521. Photo credit: ANNA-NEWS.

The Nikitin machine gun is notable for its unique push-through feed system for the rimmed 7.62x54 cartridge. This system is achieved using an experimental non-disintegrating belt for 100- and 250-round ammunition boxes.

The development of the Nikitin system progressed slowly from 1955 to 1961, while the Kalashnikov machine gun was designed more quickly, in just three years, from 1958 to 1961. A significant contributing factor was that the PK’s design closely resembled that of the current service rifle, the AK. This meant that much of the necessary technological equipment and tools were already available for the serial production of the Kalashnikov machine gun.

PK/PKS General Purpose Machine Gun. Photo by Lynndon Schooler.

By 1958, the Nikitin design was recommended for adoption, and a pilot order of 500 to 1,000 guns produced at the Kovrov Mechanical Plant was placed for field trials with troops. Due to the slow development of the Nikitin machine gun, the Soviet Army sought to accelerate the process by introducing Mikhail Kalashnikov’s design team to develop a competing design.

In conclusion, if the Nikitin machine gun had worked more quickly, Russia might have had a different general-purpose machine gun, and we might not have known about the PK machine gun. This would have significantly influenced Soviet small arms in a direction different from what we see today.

BKS .338 medium machine gun. Photo by FK BRNO.

The .338 Norma Magnum has been a prominent topic for bridging capability gaps in military applications for over a decade. Domestic and international defense contractors actively seek to enhance overmatch and increase lethality while reducing the weight to get a larger caliber in the fight. One notable company in this arena is FK BRNO, a Czech defense firm specializing in the design and manufacture of firearms. FK BRNO recently developed the BKS .338 medium machine gun, unveiled at the Eurosatory 2024 defense exhibition. It was an unexpected development since this was the company’s first machine gun design.

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The .338 caliber machine gun has attracted increased interest from the U.S. military due to the superior velocity and kinetic energy provided by the .338 Norma Magnum cartridge. The main goal of the U.S. led .338 caliber machine gun program is to counter the PKM, which has an effective range with a rear sight graduated up to 1,500 meters. However, the PKM can shoot that far, and so does the M240. Typically, the PKM is used at ranges of no more than 600 meters, serving primarily as the squad’s automatic weapon.

The .338 caliber machine gun is designed as a lighter alternative to the M2 Browning machine gun, providing a caliber advantage on the battlefield for gun teams. While one person can operate the BKS, it is best used as part of a weapons squad to leverage its capabilities fully.

BKS specifications. Photo by FK BRNO.

The Gun

The BKS is a PK-inspired, gas-operated, belt-fed, air-cooled, select-fire machine gun chambered for the .338 Norma Magnum (8.6x63 mm) cartridge. The weapon system weighs 24.2 lbs. (11 kg) and measures 50 inches (127.5 cm) in length. The BKS has a very controllable rate of fire of 550 rounds per minute, an effective range of 1,700 meters, and a maximum ballistic range of 6,500 meters. The .338 Norma Magnum reaches transonic speeds around 1,700 meters, depending on environmental factors. The available data does not explicitly state the barrel length or the twist rate.

PKM. Photo by Lynndon Schooler.

The BKS features a two-stage feed system based on the PK design. This design helps reduce the weapon’s weight using a shorter receiver than a push-through belt system. The system operates by delinking the cartridge from the belt with a cartridge grabber, which then allows the cartridge to drop into an intermediate position until the sear falls. At that point, the bolt engages and chambers the cartridge.

.338 NM in a PKM feed tray. Photo by Lynndon Schooler.

FK BRNO opted for the PK design because it offers a proven, mechanically reliable, and well-tested operating system. The receiver and feed cover are machine-forged steel, and the quick-change barrel feature from the PK design has been retained. The carrying handle’s camming action, which is used to dislodge a stuck barrel, has also been preserved.

The weapon uses a non-disintegrating metal belt for ammunition, as with the PK system. Notably, the recoil is reported to be relatively mild for a .338-caliber firearm, comparable to that of a 7.62x51, likely due to its buffer assembly and the large, highly effective muzzle device. The Soviets experimented with this type of system in PKs after capturing the M-60s during the Vietnam War, but they deemed it unnecessary for the PKM in 7.62x54. The barrel features a PKT-style three-position gas regulator. With the stock removed, I couldn’t see any buffer system. But the stock connects to a boot with a lip and a locking pin.

An M1913 Picatinny rail is integrated into the feed tray cover for mounting optics, while backup iron sights are installed on the feed tray cover and the combination front sight gas block using the M1913 rail. Additionally, a section of the M1913 rail is milled into the bottom of the front part of the receiver to allow for the attachment of a bipod to the weapon.

The BKS is designed with the standard PK-style tripod mounting points, indicating its compatibility with the Stepanov tripod. However, this tripod has several shortcomings, especially for a system intended to extend ranges. I presume that the company is aware of these issues and likely has a solution in mind.

The .338 NM caliber fills the gap between the 7.62x51mm and the .50 BMG/12.7x99mm calibers, providing overmatch capability to counter the 7.62x54 PKM weapon system while being lighter than a US M240. It also offers a compelling range, such as the M2 Browning Heavy Machine Gun. The BKS system allows users to achieve the performance of a 12.7x99-caliber weapon in a one-man, portable package. Additionally, the BKS .338 effectively doubles the kinetic energy of the PKM.

SIG .338 NM belt. Photo by Lynndon Schooler.

The company has stated that a European country has shown interest in the BKS and that FK Brno is open to future licensing agreements for the design. However, no further details have been released yet. When I reached out for comment, I did not receive a response.

The BKS showcases its heritage through the PK machine gun, renowned for its reliability and effective operating system. While limited information about this weapon system is available, it has particularly impressed me. I closely follow developments related to the PK and would love the opportunity to examine and test one.

PKMs and Stepanov tripod. Photo by Lynndon Schooler.

The BKS retains a two-stage feed system, which helps reduce weight by allowing for a shorter receiver. Additionally, this design enables the use of polymer-disintegrating links with a closed loop, further contributing to weight reduction. The BKS would be an excellent option for countries still using the PKM, such as Finland, Poland, Serbia, and Armenia.

Conclusion

Once the US finalizes its .338 NM MMG, this trend reflects military procurement strategies aimed at acquiring advanced weapon systems that enhance operational effectiveness. The BKS .338 offers improved performance in a lightweight package, meeting the military’s requirements for extended shooting distances or closer engagements with increased kinetic energy.

Specs:

· Caliber: .338 Norma Magnum (8.6x63)

· Weight: 24.2 LBS. (11 kg)

· Length: 50 inches (127.5 cm)

· Disassembled: 30 inches (76.2 cm)

· Rate of Fire: 550 rounds/min

· Effective range: 1700 meters

· Max Range: 6500 meters

· Muzzle Velocity: 2723 fps (830 m/s)

PU-2 dual-feed light machine gun with a 200-round ammunition box. Photo by Lynndon Schooler.

Light machine guns and automatic rifles emerged shortly before the First World War to enhance infantry units’ firepower. By the end of World War II, these weapons were typically employed within a fire team or squad. In modern military structures, infantry units are organized around tactics that emphasize the use of light machine guns for suppressive fire. In the early 1970s, the Soviet Union recognized the need to enhance infantry squad firepower, having previously moved from the RPD to the RPK, thus leaving a huge capability gap. While the RPK light machine gun was in service, it functioned more like an automatic rifle, with limited effectiveness due to its volume of fire. In response to this need, the development of the 5.45x39mm light machine gun program, known as “Poplin,” was initiated in 1973 by order of the USSR’s Minister of Defense.

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5.45 stuff, including the RPK-74. Photo by Lynndon Schooler.

From 1973 to 1978, work was carried out at the Izhevsk Machine-Building Plant. The all-star design team for the various versions included Y.K. Alexandrov, V.M. Kalashnikov (son of Mikhail Kalashnikov), and M.E. Dragunov (son of Yevgeny Dragunov). This development was part of the “Poplin” R&D program, funded by the Soviet Army, aimed at creating a new 5.45mm light machine gun. The goal was to achieve a 1.5- to 2-fold improvement over the existing RPK light machine gun. Basically, it achieves the firepower of the previously replaced RPD.

To increase efficiency, the development focused on creating a machine gun with a new combined feed system that could utilize magazines and belts. Including a belt feed would have been enough to significantly enhance the light machine gun’s performance for the Soviets, but they wanted to try new features. At the time, the dual-feed feature was gaining popularity. It is possible that the Soviets were inspired by their observations and chatter of FN Herstal, where Ernest Vervier was working on the FN MINIMI, a light machine gun. The prototype was released in 1974, and the US Army evaluated it in 1975. FN introduced its dual-feed system between 1975 and 1976.

With the introduction of the 5.45 mm cartridge, efforts to improve the practical rate of fire for light machine guns continued during this period, as the 7.62x39 cartridge began to transition to the newer cartridge. As part of the experimental design project “Poplin,” engineers at the Izhevsk Machine-Building Plant focused on four key areas: large-capacity magazines, belt-fed machine guns, specialized feed devices, and machine guns with combined or dual feed systems.

The Guns

Though significantly miniaturized, all versions operated with a newly developed push-through belt inspired by the NSV machine gun. It was, in Soviet fashion, a non-disintegrating design. From what I could find, no Rakov machine or belt loader was developed.

PU-1 dual-feed light machine gun, developed on a modified RPK. Photo credit unknown.

The PU light machine gun was designed with a combined feed mechanism to compete with, or investigate, what the West was doing at the time. This was nothing new, as the Czechoslovak-designed Vz. 52 light machine gun was the first to do this, and it was adopted in 1952. The PU underwent testing, where recommendations were made for conducting field tests. After modifications, the machine gun was designated the PU-1. A negative aspect is that, as a modified RPK, the system operates via a closed bolt, but it features a gas regulator to better suit a dual-feed system. In 1976, the PU-1 was successfully tested by the Ministry of Defense.

The PU-2 dual-feed light machine gun features a top folding stock. Photo credit unknown.

In 1977, the model was radically changed. The gas system was moved under the barrel and more in line with a traditional belt-fed machine gun. Here, the weapon follows the FN Minimi more closely, with the magazine serving only as a secondary feature for emergencies. The new machine gun was assigned the designation PU-2.

The PU-2 had a unique feature: it could change the direction of the belt feed, which made its design more complex and unnecessary for a light machine gun. The PU-21 introduced a gas regulator to accommodate both magazine and belt feeding. Using a belt feed requires more energy to pull the belt and ensure reliability. In contrast, a magazine feed requires less gas and a slower bolt velocity for proper feeding from the magazine.

PU-21 dual-feed light machine gun. Photo credit unknown.

The last version is the PU-21. The ability to change feed direction was ditched. The layout remained the same. The system is now operated with an open bolt.

PU-2 with a 45-round magazine and a 200-round ammunition box. Photo credit unknown.

Thoughts and Conclusion

All the systems show significant change as the project evolved, though none featured a removable barrel. This is not a bad thing, as I’ve covered before: the Soviets don’t usually change barrels for sustained fire, whereas, at least in training, we do. With a fixed barrel, this reduces weight and dispersion, both of which are wins. The necessity of a dual feed system is more a matter of novelty than necessity. For the warfighter, it adds weight and can lead to reliability issues that can reduce combat effectiveness; for the big Army, it increases production time and cost with very little return.

The PKM (M84) and the RPK. Photo by Lynndon Schooler.

In the mid-1970s, the Soviet Army did not fully recognize the need for a dual-feed system, leading to the project’s termination in 1978. Theoretically, a simple solution would have been to eliminate the dual-feed feature and instead develop an effective belt-fed 5.45mm light machine gun. However, the RPK-74 continued to serve as the Soviet light machine gun or automatic rifle. As Russia re-evaluates the need for a 5.45mm light machine gun, it will be interesting to see if the new models gain more traction.