.45 ACP Ammunition

The "Cartridge, Caliber .45, Ball, M1911" is a pistol and submachine gun cartridge intended for use against personnel and light material targets. It is famously associated with the Colt M-1911 Automatic pistol. It is also called ".45 ACP" where the initials stand for "Automatic Colt Pistol".

Cal. .45 Ball Ammunition
Cal. .45 Ball Ammunition
Photo courtesy The Sportsman's Guide.

Today in WW II: 22 Sep 1943 Operation TOENAILS completed, with the occupation by US troops of all important islands in the New Georgia group, Central Solomons.  

.45 ACP Cartridge History

.45 ACP Cartridge

The .45 ACP Cartridge was conceived in the early days of the 20th Century. In 1904, the Frankford Arsenal and commercial manufacturers were asked by the U.S. Government to develop a .45 caliber pistol cartridge. Winchester and Colt, working together, developed a response released in 1905 as the ".45 Automatic Colt" matched to a new Colt pistol chambered for the cartridge.

The cartridge/pistol combination was quite successful but not satisfactory for U.S. military purposes. Over the next few years a series of improved designs were offered, culminating in the adoption in 1911 of the "Cal. .45 Automatic Pistol Ball Cartridge, Model of 1911", a 1.273 inch cartridge with a bullet weight of 230 grains. The very first production, at Frankford Arsenal, was marked "F A 8 11", for the August 1911 date.

The cartridge was designed by John Browning of Colt, but the real influence over the choice of cartridge for the new Army pistol was Gen. John T. Thompson, (yes, the same Thompson as in Thompson submachine gun), a member of the Army Ordnance. Thompson insisted on a real "man stopper" pistol, following the poor showing of the Army's .38 Long Colt pistols during the Philippine Insurrection (1899-1902).

Thompson and Major Louis Anatole LaGarde of the Medical Corps arranged tests in 1904 on cadavers and animal remains in the Chicago stockyards, resulting in a finding that the .45 was the most effective pistol cartridge. They noted, however, that training was critical to make sure a soldier could score a hit in a vulnerable part of the body.

In addition to its use with the M1911 pistols, the .45 ACP is used in the Thompson submachine guns, and the M-3 submachine guns as well as service revolvers Colt M-1917 and the Smith and Wesson M-1917.

The .45 ACP Cartridge in 2006

In 1985 the .45 ACP M1911A1 pistol was replaced by the M9 Beretta 9mm pistol as the main sidearm of the U.S. military, although Special Forces and others continued to use the M1911A1 or other .45 ACP pistols. In August 2005, the DoD issued specifications for the Military Forces Joint Combat Pistol (JCP), a possible replacement for the M9 Pistol. The specification requires the JCP to be chambered for .45 ACP ammunition. The JCP procurement was postponed in 2006, but it seemed clear that the days of the M9 9mm pistol were coming to an end and that its replacement will mark a return to the .45 ACP cartridge.

.45 ACP Cartridge Description

The ball bullet consists of a metal jacket surrounding a lead alloy core. The bullet tip is unpainted. The case is brass. The service grade Ball M1911 has a weight of 331 grains in a length of 1.275 inches. The bullet weight is 230 grains. Muzzle velocity is 885 fps as measured by the Army.

There are a number of cartridges in the .45 ACP family for the variety of military uses:

  • Cartridge, Caliber .45, Wad Cutter
  • Cartridge, Caliber .45, Ball, High Pressure Test, M1
  • Cartridge, Caliber .45, Blank, M9
  • Cartridge, Caliber .45, Tracer, M26
  • Cartridge, Caliber .45, Line Throwing, M32
  • Cartridge, Caliber .45, Ball, M1911
  • Cartridge, Caliber .45, Ball, Match, M1911
  • Cartridge, Dummy, Caliber .45, M1921

To use the Ball cartridges in revolvers, such as the M1917 Pistols, they must be assembled in half-moon clips that hold the rimless cartridges in proper position and also serve as a speed loader.

Under NSN 1305-00-555-7077 the ammunition nomenclature is Cartridge, Caliber .45, Ball, M1911. It is packaged 50 rounds per carton, 20 cartons per M2A1 metal ammo can, 2 cans per wirebound box, 36 boxes per pallet.

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