russia’s shortage of machine guns has been evident for quite some time. Despite the so-called “legendary Kalashnikov,” russian troops have begun receiving rather unusual models. Notably, in November last year, North Korean Type 73 machine guns were documented in enemy hands, and now, Soviet-era TKB-521s from the late 1950s have appeared on the battlefield.
One of Ukraine’s Defense Forces units captured a TKB-521 as a trophy, directly confirming that the enemy has been using these machine guns for some time. Until now, the TKB-521 could primarily be seen in the exhibition of the Tula Museum of Weapons.
The TKB-521, also known as EPN (after its designer—“Ediny Pulemyot Nikitina”), was developed in 1953 at the Tula-based TsKB-14. Around 1,000 units were produced for testing. However, it ultimately lost the competition to the PK—the Kalashnikov machine gun, which entered service in 1959, relegating the TKB-521 to storage.
The reason for the PK’s victory was that the TKB-521 was “born in agony.” By 1961, when the decision to adopt a new machine gun was made, it had already undergone eight years of development. Kalashnikov himself wrote that the slow pace of the TKB-521’s designers was the main reason for their failure. Additionally, the PK’s production was facilitated by existing technological equipment and the unification of several components with the AK.
The TKB-521 had a rate of fire of 650–700 rounds per minute and weighed approximately 9 kg, making it nearly identical to the PK in key parameters. However, during final testing, the TKB-521 demonstrated better resistance to dust compared to the Kalashnikov machine gun but was less reliable when exposed to moisture. It also had advantages in loading and unloading but was inferior in assembly, disassembly, and maintenance.
One distinctive feature of the TKB-521 is the cutoff of propellant gases after striking the piston, along with a check valve that blocks the gas tube outlet. This required the production of components with extremely strict tolerances and nearly individual fitting.
Another notable feature is its direct cartridge feeding mechanism, which inserts rounds from the belt straight into the chamber. This differs from the PK, where cartridges are first pulled back and down from the belt before being chambered. As a result, the TKB-521 required a special belt link design, meaning it used proprietary belts incompatible with existing SGM and RP-46 machine guns. The PK did not suffer from these limitations.
Reports suggest that in Moscow, officials either forgot about the TKB-521’s belt compatibility issue or simply never produced the required belts. Regardless, this did not prevent them from officially issuing the necessary number of machine guns on paper. This explains why, in photos of the captured sample and those taken by russian troops, the machine gun appears without its belts.