The .45 ACP was designed by John Moses Browning and introduced in 1905. The U.S. military needed a cartridge to replace the .38 Long Colt cartridge, the performance of which was “less-than-stellar.” Originally the .45 ACP had a 200 grain bullet that traveled 900 feet per second. The .45 ACP cartridge and the M1911 pistol were tested by the U.S. Army over the next six years, where both the ammunition and the firearm were modified. The bullet weight was increased to 230 grains without a change in the powder load, so muzzle velocity for this new bullet dropped to 830 feet per second. This remained the standard load for the service life of the .45 ACP.
Sgt. Alvin York in World War I used his .45 ACP to singlehandedly kill 6 German soldiers while assaulting their machine gun emplacements, supporting the claim of the cartridge as an excellent man stopper. While his story is one of the more famous, other Medal of Honor recipients besides York used the .45 ACP. Since being adopted in 1911 by the military, at least 68 awardees of the Medal of Honor have carried the .45 ACP and the M1911 pistol in the course of their heroic actions.
The .45 ACP is used outside of the Armed Forces in a plethora of applications that include sport shooting, law enforcement and self-defense. Target shooters appreciate the .45 ACP for its accuracy, mild recoil and heavy bullet. Major ammunition manufacturers produce .45 ACP in specialty configurations just for personal protection . Hornady, Federal and Magtech are a few of the companies that regularly refine and introduce new .45 ACP ammo for personal protection.
The .45 ACP is issued or permitted for use by many law enforcement agencies for their officers and agents. Agencies which have chosen the .45 ACP for its proven ability to effectively stop dangerous aggressors include the FBI’s Hostage Rescue Team, the Los Angeles Police Department SWAT, and other specialized law enforcement units. The U.S. military officially replaced the .45 ACP with the 9mm in 1985, though it continues to find pockets of dedicated users in the Service. Operators of the Marine Expeditionary Units, Delta Force and others within the purview of the United States Special Operations Command have the option of using pistols chambered in the .45 ACP.
The .45 ACP, after more than a century of use, is a cartridge that has been modified and studied extensively, and used all over the world. It remains today one of the most prized cartridges on the market.