Concept
The 12.7×108mm cartridge is a 12.7 mm heavy machine gun and anti-materiel rifle cartridge used by the former Soviet Union, the former Warsaw Pact countries, modern Russia, China and other countries. It was invented in 1934 to create a cartridge like the German 13.2mm TuF anti-tank rifle round and the American .50 Browning Machine Gun round (12.7×99mm NATO). It is used in the same roles as the NATO .50 BMG (12.7×99mm NATO) cartridge. The two differ in bullet shape and weight, and the casing of the 12.7×108mm is slightly longer, and its larger case capacity allows it to hold slightly more of a different type of powder. The 12.7×108mm can be used to engage a wide variety of targets on the battlefield, and will destroy unarmored vehicles, penetrate lightly armored vehicles and damage external ancillary equipment (i.e.: searchlights, radar, transmitters, vision blocks, engine compartment covers) on heavily armored vehicles such as tanks. It will also ignite gasoline and—since 2019—diesel fuel (experimental "Avers" AP/I round). The 12.7×108mm has 22.72 ml (350 grains) H2O cartridge case capacity. 12.7×108 maximum cartridge dimensions. All sizes in millimeters (mm). Americans define the shoulder angle at alpha/2 ≈ 18.16 degrees. According to guidelines the 12.7×108mm case can handle up to 360 MPa (52,213 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum CIP pressure to certify for sale to consumers. Б-30 / B-30 First version of 1930. Armor-piercing (бронебойная) bullet weighing 49 g and 64 mm long with hardened steel core. Replaced by B-32. БЗТ / BZT Pre-WW2 armor-piercing incendiary (зажигательно) tracer. Replaced by BZT-44. Б-32 / B-32 (GRAU# 57-BZ-542, 7-BZ-2) Steel-cored () bullet. Main type in use. Penetrates 20mm NATO medium-hard RHA from 500m at 0° when fired out of DShKM. Penetrates 20mm 2P steel from 100m at 0° when fired out of NSV-12.7. First produced 1936; named after the B-32 7.62×54mmR ammunition of 1932. БС-41 / BS-41 API bullet weighing 55.
