The M2 machine gun or Browning .50 caliber machine gun is a heavy machine gun that was designed near the end of World War I by John Browning. While similar to Browning's M1919 Browning machine gun, which was chambered for the .30-06 cartridge, the M2 uses Browning's larger and more powerful .50 BMG cartridge. The design has had many designations; the official U.S. military designation for the infantry type is Browning Machine Gun, Cal. .50, M2, HB, Flexible. It has been used against infantry, light armored vehicles, watercraft, light fortifications, and low-flying aircraft.

An ammunition belt is a firearm device used to package and feed cartridges, typically for rapid-firing automatic weapons such as machine guns. Belt-fed systems minimize the proportional weight of the ammunition apparatus to the entire weapon system, and allow high rates of continuous fire without needing frequent magazine changes. The capacity of belts and associated belt containers is typically a function of weight and bulk, and their size is limited by caliber and the combined portability of the weapon and ammunition. Typical capacities for man-portable weapon systems range from 50 to 300 rounds of ammunition.