.50 BMG - Cartridge Dimensions

Cartridge Dimensions

The 50 BMG 12.7 × 99 NATO cartridge has a capacity of 290 grains H₂O (19 ml). The round is a scaled up version of the .30-06 Springfield but uses a case wall with a long taper to facilitate feeding and extraction in various weapons.

50 BMG basic cartridge dimensions-All sizes in inches (in). The common rifling twist rate for this cartridge is 1 in 15 in (381 mm), with 8 lands and grooves. The primer type specified for this ammunition is Boxer primer that has a single centralized ignition point (US and NATO countries). However, some other countries produce the ammunition with Berdan primers that have two flash holes.

Average chamber pressure in for this round as listed in TM43-0001-27 the U.S. Army Ammunition Data Sheets —Small Caliber Ammunition, not including plastic practice, short cased spotter, or proof/test loads, is 54,923 PSI (378 MPa or 3,787 bar). The proof/test pressure is listed as 65,000 psi (448 MPa or 4,482 bar).