.50 Caliber Ammunition

The .50 cal. cartridge was developed for use with the Browning .50 cal. machine gun, in use since immediately after World War I. It has remained in use since as one of the main weapons for infantry, aircraft, armored vehicles, naval vessels and other applications of the versitile weapon. The heavy .50 cal. rounds were originally packed into wood .50 cal. boxes, later into steel chests or .50 cal. ammo cans. For aircraft and other platforms, the rounds are stored in special containers in the gun bays, almost always in long belts.

Belted .50 cal. ammunition to be loaded on  B-29 bombers, 29 November 1944
Belted .50 cal. ammunition to be loaded on B-29 bombers, 29 November 1944.

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.50 caliber Cartridges Description

The .50 caliber Browning Machine Gun (BMG) cartridge was developed following the First World War as a heavy machine gun cartridge. It was adopted by the U.S. Army in 1923, and has been in continuous service since that time.

The dimensions of the .50 caliber M2 Ball round are shown in the drawing on the left (from TM 43-0001-27, Army Ammunition Data Sheets, Small Arms). The 709 grain FMJ bullet is measured at 3050 fps for the M2 Ball round in the M2 machine gun (USMC data). The weight of 100 rounds of linked M2 ball in ammunition can is approximately 35 pounds.

The caliber .50 cartridge consists of a cartridge case, primer, propelling charge, and the bullet. There are more than 20 types of ammunition issued for use in the caliber .50 machine gun, color coded on the tip to enable identification of loose rounds, tabulated below. The ammunition is fed to the machine gun linked with the M2 or M9 metallic links in disintegrating belts.

Types of U.S. .50 cal. Cartridges

This listing of .50 cal. cartridges includes most of the types used by the U.S. military:

  • Cartridge, Caliber .50, Ball, High Pressure Test, M1
  • Cartridge, Caliber .50, Blank, M1 (no bullet, crimped)
  • Cartridge, Caliber .50, Incendiary, M1 (blue tip)
  • Cartridge, Caliber .50, Tracer, M1 (red, maroon, or orange tip)
  • Cartridge, Caliber .50, Blank, M1A1 (no bullet, crimped)
  • Cartridge, Caliber .50, Ball, M2
  • Cartridge, Caliber .50, Ball, Armor Piercing, M2 (black tip)
  • Cartridge, Dummy, Caliber .50, M2 (holes in case)
  • Cartridge, Caliber .50, Ball, Armor Piercing Incendiary, M8 (aluminum tip)
  • Cartridge, Caliber .50, Tracer M10 (red, maroon, or orange tip)
  • Cartridge, Caliber .50, Tracer; M17 (red, maroon, or orange tip)
  • Cartridge, Caliber .50, Ball, Armor Piercing Incendiary-Tracer, M20 (red ring/aluminum tip)
  • Cartridge, Caliber .50, Incendiary, M23 (blue tip)
  • Cartridge, Caliber .50, Ball, M33
  • Cartridge, Caliber .50, Ball, Spotter-Tracer, M48A1
  • Cartridge, Caliber .50, Ball, Spotter-Tracer, M48A2
  • Cartridge, Caliber .50, Ball, Plastic Practice, M858
  • Cartridge, Caliber .50, Tracer, Plastic Practice, M860
  • Cartridge, Caliber .50, Saboted Light Armor Penetrator (SLAP), M903 (plastic sleeve on projectile)
  • Cartridge, Caliber .50, Saboted Light Armor Penetrator-Tracer (SLAP-T), M962
  • Cartridge, Caliber .50, Ball, Practice, T249E2
  • Cartridge, Caliber .50, Ball, High Pressure Test, T251
  • Cartridge, Caliber .50: Armor Piercing Incendiary (API), MK 211 MOD 0

.50 cal. M2 machine gun with its .50 cal. ammunition cans, USMC Twentynine Palms, CA
M2 machine gun with its .50 cal. ammunition cans, USMC Twentynine Palms, CA.

Cartridge, Caliber .50, Saboted Light Armor Penetrator (SLAP)

Cartridge, Caliber .50, Saboted Light Armor Penetrator (SLAP) has a metal core penetrator that consists of a reduced caliber tungsten slug of .30 inch diameter. The penetrator is wrapped in a plastic sabot (called a shoe) that has the full .50 inch diameter. There are two configurations, ball (M903) and tracer (M962). According to Defense Industry Daily (1 Apr 2010):

The SLAP ammo is much lighter in weight than the normal ball .50 caliber ammunition, so its velocity can be significantly increased in an unmodified M2 heavy machine gun. This produces a fast round with a flat trajectory which enhances hit probability. The SLAP ammo has a velocity of 3,985 feet per second and a maximum effective range of 4,921.5 feet.

Future of the .50 cal. Cartridge

.50 cal., belted ammunition in M2A1 ammo box
.50 cal. ammo in M2A1 box.

Although in service since before 1920, the .50 cal. M2 machine gun continues in use with all branches of the U.S. services as well as around the world. The .50 cal. ammunition thus has a secure place in military procurement for many years to come, perhaps renamed as 12.7 x 99mm in metric equivalent terms. In addition, the .50 cal. cartridge has found a new application with tactical rifles such as the Barrett M82A1, long-range sniper rifles used to interdict OPFOR personnel and destroy light equipment at ranges in excess of 1500 meters.

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