.45 ACP

.45 ACP
Grasyl · CC BY-SA 4.0 · source
Name	.45 ACP
Origin	United States
Type	Pistol cartridge
Designer	John Moses Browning
Design date	1904
Produced	1905–present
Parent case	.45 ACP (original)
Bullet diameter	0.452 in (11.5 mm)
Case length	0.898 in (22.8 mm)
Overall length	1.275 in (32.4 mm)

.45 ACP The .45 ACP is a rimless, straight-walled handgun cartridge developed in the early 20th century for a short-recoil-operated, semi-automatic pistol. It was designed to meet requirements for stopping power and reliable function in service pistols adopted by armed forces and police agencies. The cartridge became closely associated with several notable designs and institutions and remains influential in both military and civilian spheres.

History

Developed by John Moses Browning during the period when Theodore Roosevelt influenced small arms policy and amid debates following the Philippine–American War, the cartridge was intended for use in new semi-automatic pistols under consideration by the United States Army. Trials and service considerations that involved figures and organizations such as the U.S. Army Ordnance Department, Springfield Armory, and the commission that evaluated handguns led to the official adoption of a pistol chambered for this cartridge in 1911. Its prominence grew through major 20th-century conflicts including World War I, World War II, and the Korean War, during which the round was employed by units from the United States Marine Corps and the United States Navy.

Design and Specifications

The cartridge uses a 0.452-inch diameter bullet seated in a straight, rimless case with a 0.898-inch case length and a 1.275-inch overall length, patterned to function in short-recoil designs exemplified by pistols produced at facilities like Colt's Manufacturing Company and Fabrique Nationale de Herstal. The original load was a 230-grain full metal jacket projectile optimized for penetration and reliable feeding in service pistols derived from Browning's design. Manufacturing standards and chamber dimensions have been standardized by organizations such as SAAMI and the CIP to ensure interchangeability among commercial and military producers including Remington, Winchester, and Speer.

Ballistics and Performance

Typical factory ballistics for a 230-grain full metal jacket yield muzzle velocities in the neighborhood of 830 feet per second from a 5-inch barrel, producing muzzle energy roughly comparable to contemporaneous service cartridges used by forces like the British Army and the Imperial Japanese Army in small arms of the era. Lighter projectiles in the 185- to 200-grain range provide higher velocities and different wound profiles; expanding projectiles from manufacturers such as Hornady, Federal Premium Ammunition, and Gold Dot are tailored for terminal performance in law enforcement contexts. Ballistic considerations also address sectional density, momentum, and wound channel characteristics that were scrutinized in reports from panels and commissions after engagements involving units like those of the U.S. Marine Corps.

Firearms and Platforms

The cartridge's history is intertwined with several iconic handguns and platforms produced by companies such as Colt's Manufacturing Company, Browning, Smith & Wesson, and Springfield Armory. Notable pistols chambered for the cartridge include models from Colt M1911-line series, variants by Glock adapted for larger frames, and modern designs from SIG Sauer and Heckler & Koch's commercial offerings. Submachine and carbine platforms, often manufactured by firms like Auto-Ordnance and Rock Island Armory, have also been built around this cartridge to provide increased controllability and terminal effects in close-quarters environments.

Ammunition Variants and Reloading

Commercial loadings span full metal jacket, jacketed hollow point, plated, and specialty projectiles including frangible and +P offerings produced by firms such as Federal Premium Ammunition, Winchester, Remington, Hornady, and boutique makers like Cor-Bon. Handloading communities—organized through clubs and publishers such as National Rifle Association-affiliated ranges and periodicals—commonly experiment with bullet weights from 185 to 230 grains, powders from manufacturers like Hodgdon and Alliant, and primers by CCI or Federal. Reloading manuals and standards from organizations including SAAMI guide safe pressures and dimensions; specialty cartridges for competition and hunting often alter bullet construction for specific terminal or feeding characteristics.

Military and Law Enforcement Use

Adopted formally by the United States Army and fielded extensively by units including the Office of Strategic Services and later special operations, the cartridge served as a primary sidearm round through much of the 20th century. Law enforcement agencies—ranging from municipal departments in New York City and Los Angeles to federal agencies such as the Federal Bureau of Investigation—utilized the cartridge in service pistols, with many transitioning to alternative calibers amid changing doctrines and procurement choices influenced by incidents involving tactical engagements and evidence presented to legislative oversight bodies.

Civilian Use and Controversies

The cartridge enjoys enduring popularity among sport shooters, competitive shooters in matches governed by organizations like United States Practical Shooting Association, hunters pursuing medium game in jurisdictions such as Texas, and collectors of historical firearms connected to institutions like National Firearms Museum. Controversies have arisen regarding terminal effectiveness, public safety debates involving municipal and state legislators, and policy discussions before bodies including state legislatures and the U.S. Congress about regulation of ammunition and firearms. Despite periodic challenges, the cartridge remains a widely manufactured and stocked caliber in commercial markets by producers such as Remington, Winchester, and Federal Premium Ammunition.

Category:Cartridges