TKB-523

In January-February 1957, comparative testing trials took place, at which prototypes of Kalashnikov AKM , Korobov TKB-517 and Konstantinov designs were tested, as well as light machine guns of the same designers that took part in the tests for the first time.

The main struggle unfolded between AKM and TKB-517. One of the features of the Korobov TKB-517 assault rifle was the use of the energy of the bounce of the bolt frame during firing, which ensured the normal operation of automation and acceptable accuracy of the battle.

In the field tests, low-trained shooters, firing continuously from the TKB-517 submachine gun from a lying position, showed the results 1.3–1.9 times better than from a standard AK submachine gun. In addition, it was possible to fire from the Korobov assault rifle, both from the right and from the left shoulder, while the accuracy did not change much, since the layout of the moving parts of the automation was central and therefore all forces acted symmetrically.

The Kalashnikov assault rifle was clearly losing the contest. To improve the accuracy of firing, a trigger delayer borrowed from the Korobov assault rifle was introduced into the Kalashnikov assault rifle, which increased the inter-cycle time.

As a result, in 1959, the 7.62-mm modernized AKM Kalashnikov assault rifle was adopted by the Soviet Army.

TKB-523 is made on the basis of automation with a half-free shutter. The bolt group consists of a light shutter and a heavier bolt frame. A two-arm lever is installed on the shutter, with the lower shoulder resting on the receiver when the shutter is in the closed position, and the upper arm into the shutter frame. At the moment of the shot, powder gases begin to press on the bottom of the cartridge case, moving it back in the chamber, because of which it presses on the shutter mirror. The upper arm of the lever drives the bolt frame. Due to the difference in shoulders immediately after the shot, the bolt moves slowly, unlike the bolt frame. By the time the pressure in the chamber decreases to a safe level, the retarder is disengaged and then the bolt with the bolt frame, compressing the return spring, move together. The cartridge case is removed and thrown away, and when the bolt group goes back, a new cartridge is fed into the chamber. The shutter handle is fixedly mounted on the shutter frame to the right.

Handguard - stamped from steel sheet. The USM design has a self-timer, which plays the role of an inter-cycle moderator and allows you to calm the vibrations of weapons. USM allows you to fire both single and continuous bursts. The translator fuse is located above the trigger guard on the right side of the receiver. An open sight with a swinging whole was fixed in the holes on the wall of the receiver, allowing the shooters to set the required range by ear (by clicks).

• Caliber - 7.62 × 39 mm;
• Length - 1020 mm;
• Weight - 3.1 kg;
• Magazine capacity - 30/75/100 rounds;
• Rate of fire - 600 rounds per min.

• TKB-408
• TKB-022
• TKB-517