|Rate of fire||800-1,050rpm|
Universal'nyj Berezina - multi-purpose machine gun designed by M.Ye. Berezin. Design of this weapons family was initiated in 1935 by a team led by M.Ye.Berezin. Their efforts reflected the international trend towards larger calibers for aircraft guns coming up at about that time. Further impetus brought the success of the 12.7mm DShK anti-aircraft machine gun introduced into service with the Red Army in 1938.
In 1939 the testing of six prototypes designated 'BS' (Berezina Sinkhronnyj) took place. These guns were installed in I-153 and I-16 fighters and were firing synchronized through the propeller disc. Compared with the DShK (Degtyaryov-Shpagin Krasnoj) gun the muzzle velocity and rate of fire had been increased and simultaneously the weight was reduced considerably.
The testing of those prototypes revealed some shortcomings, among them problems with reloading. After fixing of them, the final version was introduced into service in April 1940 under the designation 'UB'. The gun appeared in three basic variants, according to the way of installation:
Compared with the widely-used American 12.7mm Colt-Browning aircraft gun, the UB was of more compact design and fired a heavier bullet at a higher rate and with a higher muzzle velocity. All functions of the UB gun were gas-operated. In 1945 its performance was further improved. The gun could fire different types of bullets, denoted by a color code on the ammunition: