Berezin UB
The Berezin UB (Russian: УБ - Универсальный Березина) (Berezin's Universal) was a 12.7 mm caliber Soviet aircraft machine gun widely used during World War II. == Development == In 1937, Mikhail Berezin began designing a new large-caliber aircraft machine gun chambered to the 12.7 mm round used by infantry machine guns. The new design passed factory trials in 1938 and was accepted into service in 1939 under the designation BS (Березин Синхронный, Berezin Sinkhronniy, Berezin Synchronized).