RB-Model 72B34 Lufa B-3, BT-2 37 mm

B-3 (5-F) is a 37 mm tank gun from the interwar period and the early period of World War II, produced by the Soviet Union. The first prototypes of the gun were created in the early 1930s, and serial production started shortly after. The 37mm B-3 tank gun was a relatively simple modernization of the M1930 (1-K) anti-tank gun of the same caliber. The latter was produced in the years 1931-1932 and was the first specialist anti-tank department. put into service with the Red Army. The cannon fired bullets 37 × 257 mm R, and its barrel length was 42 calibers, or 155.4 centimeters. The average maximum speed of a shell fired from this gun was up to 800-850 m / s, and the rate of fire - with a well-trained crew - ranged from 10 to 15 rounds per minute. It is worth noting that both the M1930 gun and the B-3 gun were clearly structurally based on the German 37mm PaK 36 gun. The B-3 gun was the main armament of the BT-2 fast tank.