From Goryunov’s SG-43 To Kalashnikov’s PK

The PK and PKM can be traced back to the Goryunov SG-43 medium machine gun, a testament to the unwavering perseverance of Kalashnikov’s design team. Their dedication and hard work in refining the machine gun are genuinely inspiring. This historical evolution, from the SG-43 to the PK series, carries significant weight in the field of military technology.

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In 1941-42, Pyotr Goryunov developed a light machine gun in the Soviet 7.62x54R cartridge from 1891. The light machine gun was the GVG for Pyotr Goryunov, Vasily Voronkov, and Pyotr’s nephew Mikhail Goryunov. The GVG resembled a DP-27 by V.A. Degtyarev, though lighter in design, and initially, this was the Soviet Union’s first dual feed system, pan magazine or belt fed. The magazine feed feature was dropped in 1942. This would have given the Soviet Union a light machine gun with increased firepower compared to the limited capacity of the pan magazine-fed DP-27 and later the DPM, which would have been one of the earliest concepts of a Soviet general-purpose machine gun.

Unfortunately, there was a greater need for medium and heavy machine guns requested by the military. In late 1942, the stamped gun was switched to a milled medium machine gun; this design resembled the prototype Degtyarev DS-42 heavy machine gun. This created the SG-43 medium machine gun, which was rushed into service to replace the M1910/30 Maxim guns; this rapid fielding resulted in unforeseen shortcomings.

This was previously attempted to replace the Maxim before the war in 1939 with the DS-39. However, shortly after the adoption of the DS-39, production of the M1910/30 was stopped and restarted after the unadopted DS-39 due to its poor reliability and removal from service. With the SG-43, numerous breakages were reported in its early stages, such as issues with the feed tray cover and a reliable system to delink the rimmed cartridge. There were no provisions to prevent the ingress of dirt in the action, which hampered the weapon systems’ reliability. Unfortunately, in late December 1943, Pyotr Goryunov died at 42; he was in the early stage of refining his creation.

The evolution of the SG-43 to the PK series was significantly influenced by the work of M.T. Kalashnikov and his team of talented engineers. Their contributions played a crucial role in the improvement of the machine gun. In its early stages, Kalashnikov developed the cartridge grabber, which delinks the cartridge from the belt and brings it to an intermediate feeding position at full bolt carrier travel. Once fired, the bolt picks up the cartridge and moves it to the chamber, where once locked, it fires and repeats the function. Though his design was not used in the modernized SG-43, his modified and simplified carried over to the PK series.

The barrel locking block Kalashnikov designed was unique in that it could adjust the headspace. Though again not used in the final SG-43, he developed a refined method of changing the weapon headspace, which was finally seen in the PK series. Also carried over was the recess, which used a cartridge to manipulate the barrel locking block to unlock and change barrels when stuck due to poor maintenance or heat.

Kalashnikov developed a spring-loaded dust cover for the ejection port cover, significantly reducing the ingress of dirt. His later PK design would see dustcovers on every opening, the ejection ports, and feed tray cover spring-loaded dustcovers. Other elements Kalashnikov helped upgrade were a right-side charging handle, trigger mechanism, rear sight, and the moving of the cartridge grabber from the separate feed tray assembly to affixed to the bolt carrier, making it a removable component for replacement. This also allowed for easier manufacturing. Some of these features were not seen in the final adopted design.

All these updates by the combined design team led to the creation of the modernized SG-43, and the result was the adoption of the Goryunov modernized heavy machine gun, the SGM.

All the updates in the design experience were carried over to Kalashnikov’s development into the PK series of machine guns. In 1958-1959, his first experimental prototype, factory index E-2, was of milled construction, the standard material and production method of Soviet belt-fed machine guns of the day. This would later change before the adoption of the weapon in 1961 to a stamped receiver.

At the same time, Kalashnikov worked on the lightweight stamped AK rifle, which would become the AKM, and the light machine gun, which would become the RPK. The change considerably reduced the overall weight, making the weapon more mobile, easier for end users, and easier to manufacture.

The PK was the Soviet Union’s first universal or general-purpose machine gun, a significant milestone in the history of military technology. It turned out to be one of the most successful general-purpose machine guns. With such a reliable and straightforward operating system, the two-stage feed system led to a very short receiver, and overall, this reduced the weight of the machine gun. This feature was not revolutionary and was seen in earlier machine gun designs, but the combinations and simplification created an unrivaled machine gun worldwide.

Kalashnikov’s early work and interactions with many talented engineers led to his successful future. He and his design teams created some of the most frequently encountered weapon systems on the battlefield today, contributing to a reliable and successful design and proliferation through Soviet political diplomacy.

The legacy of the PK and the modernized successor, the PKM, has been seen and encountered in every hot spot since its inception. The PKM’s role in modern warfare is not just significant; it’s transformative. With potential future modifications for mounting accessories to new calibers to increase the over-match capability over potential adversaries, the PKM is shaping the future of infantry firepower.

In its current standard configuration, the PKM has been pushed from a platoon machine gun to a squad light machine gun role, with some nations having one PKM per fire team, giving two guns per squad, significantly increasing an infantry squad’s firepower, thus enhancing the potential unit’s lethality. This alone provides an overmatch with the current 5.56-based squad automatic weapons, underscoring the PKM’s pivotal role in improving infantry firepower.

Pictures by the author