In 1937. M.E. Berezin started to project high-power 12.7-mm a synchronous air machine gun with the cartridge from 12.7-mm of an infantry machine gun. In October - December, 1938 the synchronous machine gun has successfully passed factory and range tests. On April, 12, 1939 12,7-mm machine gun BS (Berezin Synchronous) has been launched by the decision of Committee of Defense in series production.

Automatics of a machine gun worked due to energy of the gases assigned from a bore.

To advantages of a machine gun Berezina concerned: successful layout of all automatic control unit and separate gears; high rate of shooting; simple loading and unloading, elimination of delay and fast change of a trunk; rather a small number of details and the simple device of the gear.

Despite of all positive qualities, BS machine gun had some serious lacks. Difficulty of its reload in air with the help of the cord system demanded of the pilot the big physical efforts in the most decisive minutes of battle especially affected; the defects connected to insufficient survivability of separate details of automatics have come to light.

Working above the further perfection of the system with a view of liquidation of these lacks and creation of a universal machine gun for its application in the main firing points of all machine guns, M.E.Berezin has developed universal machine gun UB (Universal Berezin) in three versions depending on an installation site - turret, wing and synchronous. The basic details and gears of all three versions of a machine gun have been kept, except for trigger and impact gears in which some changes connected to specificity of their application have been brought. In synchronous (UBS) and wing (UBK) versions remote control by a system recharge has been carried out in case of occurrence{appearance} of stoppages in air with use of compressed air. It was the system of a pneumatic reload of the machine gun first in the Soviet aircraft, considerably facilitated its operation in battle conditions.

During tests machine gun UB trouble-free worked at a 9-kilometer altitude at ±48 °С, continued to shoot in steep turns, battle turns, loops, and diving.

Weight of a machine gun Berezina in synchronous version 21.45 kg, wing - 21.14 kg, turret - 21.43 kg. Rate of shooting in synchronous version 700-800 of shots/minutes, wing and turret 800-1050 shots/minutes. The ammunition load and ballistics are identical from 12.7-mm ShVAK machine gun.

From January, 7 till February, 22, 1941 the machine gun Berezina successfully passed service trials.

The universal Berezin machine gun has been introduced into the inventory by air force on 22 April 1941. The 12.7-mm UB machine gun has got ready in time for the war which has begun through two month has revealed an ineffectiveness of 7.62-mm of air machine guns at shooting on air targets.

Manufacture of machine guns UB was conducted on Tula weapon and Izhevsk plants.

In 1941 6300 UB machine guns, in 1943 - 43690, in 1944 - 38340, in 1945 - 42952 have been have been released.

The synchronous machine gun Berezina was established set on fighters I-15, I-153bis,Yak-1B, Yak-3, Yak-7B, Yak-9, the MiG - 3 and LaGG-3.

Bibliography

• "The history of air armament." /Alexander Shirokorad/