Nikitin TKB-521 machine gun is an interesting weapon which almost became the standard issue GMPM for the Soviet Army, but then suddenly lost the final trials to a rapidly emerged Kalashnikov PK machine gun.
Nikitin TKB-521 machine gun
Soviet designers began serious work on general purpose (universal) machine guns during the WW2, as soon as Soviet troops faced German MG-34 and MG-42 machine guns. First official technical requirements for a new universal machine gun were drawn by GAU (General Artillery Department of the Soviet Army) in 1947, and the work commenced in two design bureaus, in the cities of Kovrov and Tula.
However, designing a new GPMG proved to be a hard task. In 1955, with no end in sight, GAU updated its requirements, lowering the weight threshold (on bipod) from 13 to 9 kg. Also, requirements suggested the use of a push-through, non-disintegrating steel belt, similar in concept to the German Gurt-34 belt, used in MG-34 and MG-42. Use of the older, pull-out steel belt, originally designed for the Goryunov SG-43 machine gun was permitted but not encouraged.
The most promising design that was based on 1955 requirements was the TKB-521 machine gun, designed by Nikitin in the TsKB-14 design bureau in Tula. Work on this weapon commenced in 1955, and its first trials started in 1957. In 1958 Ministry of Defense ordered a small batch of several hundreds Nikitin machine guns to be made at Kovrov mechanical plant for extended field trials.
Nikitin TKB-521 machine gun
Despite this progress, not everyone at the GAU was happy with the slow progress of the work, which by that time took more than 10 years. Also, some experts saw the TKB-521 as an overly complex and insufficiently reliable weapon, especially when it was subjected to water. To spur up the race, in 1958 the MoD invited Mikhail Kalashnikov, an already established gun designer, to take part in the trials. As a result, within a very short amount of time Kalashnikov was able to produce a machine gun that was simpler and cheaper to make than Nikitin machine gun, easier to maintain in the field, and more reliable. Last but not least the Kalashnikov machine gun made use of older SG-43/SGM belts, which were very plentiful and which manufacture posed no risks. On the other hand, new belts for Nikitin machine guns posed obvious risks of teething problems, and also were harder to load by hand. Therefore, after much comings and goings and numerous updates, in 1961 Soviet military finally selected the Kalashnikov PK machine gun over the Nikitin PN / TKB-521. It is interesting to note that Kalashnikov machine gun was tested and adopted along with a modified Samozhenkov tripod, which was originally developed for the Nikitin machine gun. Several hundreds of TKB-521 machine guns, made in 1960 for the field trials, were put into reserve storage, to resurface more than 60 years later, during the Russo-Ukrainian conflict, where several Nikitin machine guns were captured by Russian troops in 2024 and 2025.
Nikitin TKB-521 machine gun on Samozhenkov tripod
The Nikitin machine gun is a gas operated, belt fed weapon that fires from the open bolt and in full automatic only. It uses a long stroke gas piston with a large expansion gas chamber in its front, and a cut-off valve which ensures more smooth operation under normal or adverse condition. However, this system requires more close tolerances between the piston and gas chamber, a more complex design with a valve, and an additional water drain valve to avoid stoppages when gun becomes wet and water enters the gas cylinder. A manual gas regulator is added to ensure better reliability under the harsh conditions. Barrel locking is achieved by a rotating bolt, and the barrel can be quickly replaced when hot or worn out. Gun is fed using steel, non-disintegrating belts assembled from 50-round fragments. Each link is made from a springy steel and has a C-shaped cross-section, with the opening facing downward.
Nikitin TKB-521 machine gun, view to the belt feed unit
the belt for a Nikitin TKB-521 machine gun. Note that only the two cartridges on the right are set correctly; three on the left are set too far back and could cause jams if fired that way.
Each Nikitin machine gun was equipped with a wooden stock and a pistol grip; a folding bipod was attached to the gas tube. For use in a medium machine gun role, Nikitin machine gun was supplied with a TKB-552 tripod, designed in the same design bureau by Samozhenkov.
Encyclopedia of firearms and ammunition of the XX and XXI centuries
All texts are written by Maxim Popenker © 1999-2025
