What is 12.7 x 108 mm?

The 12.7 x 108 mm is a heavy machine gun cartridge used in anti-aircraft, anti-personnel, and anti-vehicle roles by numerous armed forces around the world. It was developed by the Soviet Union in the early 1930s and is similar in performance to the American .50 BMG cartridge. It has a bullet diameter of 12.7 mm (0.50 in) and a case length of 108 mm (4.25 in). The cartridge is typically used in heavy machine guns, such as the Russian DShK and NSV machine guns, and the Chinese Type 54 and Type 77 machine guns. The round is known for its high accuracy at long range and its ability to penetrate armor.