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The .45 ACP; A Very Brief History

.45 ACP Cartridge History

It can be argued that the story of the .45 ACP begins in 1892, with the adoption by the US Army of the Colt M1892 revolver in that year. The new Army/Navy M1892 sported a double action trigger, which was an improvement over the Single Action Army revolver it replaced. It was, however, chambered in .38 Long Colt, a much less powerful round than the .45 it relieved from duty, a fact that was soon to be lamented by US servicemen.

The Philippine-American War

Not long after the adoption of the new service sidearm, the US military became engaged in the Philippine islands, and the M1892 was first brought to bear in combat (by this time many revisions to the revolver had been made, with the latest iteration at the time being the M1889). Initial battlefield reports were dismal. A typical scenario was relayed by Col. Louis LaGarde, wherein he reported the case of an enemy combatant who had been taken prisoner, and had attempted escape. The man attacked his guard, who, armed with the new .38, fired 4 rounds, all of which struck the escapee. Two of the shots struck center mass, but with almost no effect. LaGarde concluded his report by saying the man was finally subdued by a blow to the forehead by the butt of a rifle. Such reports of the new revolver’s ineffectiveness led to the rapid un-mothballing and hasty issuing of old stores of Colt Single-Action Army revolvers. So much for Colt’s New Army M1892.

The Thompson-LeGarde Tests

With the need for another new service sidearm now patently clear, the Army tasked Infantry Colonel John T. Thompson, and Major Louis Anatole LaGarde of the Medical Corps, with finding a reliable, man-stopping cartridge for use in US military handguns.

The pair designed a battery of tests, conducted at the Nelson Morris Company Union Stock Yards in Chicago, Illinois, in 1904. The resulting report concluded that “…a bullet, which will have the shock effect and stopping effect at short ranges necessary for a military pistol or revolver, should have a caliber not less than .45…”

Colt and Mr. Browning

The much-celebrated collaboration between Colt’s Patent Firearms Manufacturing Company and John M. Browning began in the late 19th century, and resulted in revolutionary locked-breech designs such as the 1905, and of course, 1911 Automatic pistols. Around the time of the Thompson-LeGarde tests, Browning and Colt were busy developing a .41 caliber cartridge when the US Cavalry requested a version of the Colt 1902 Auto pistol in the newly recommended .45 caliber. Colt tapped Browning, and the great designer got to work, first developing a .45 caliber cartridge, and then adapting his 1902 pistol to the larger round. The result was the Model 1905 pistol and, though some tweaking was still in store, the .45 ACP cartridge.

Testing and Selection

In December of 1906 the Secretary of War issued a special order outlining the requirements any new handgun design would have to meet to be considered by the Military. The order specified a caliber not less than .45, a bullet weight not less than 230 grains, a magazine capacity of at least 6 rounds, and a trigger pull of at least 6 pounds. This mandate caused additional tweaking of the .45 ACP which brought it more or less to the standard specs we have today.

Testing of the candidate guns was to begin in 1906, but was delayed until 1907, when the first round was held. Only 3 guns passed this preliminary round of tests, Colt’s Browning-designed entrant being one of them. Changes were requested, and designs were improved and retested, until the Colt, and a pistol from Savage Arms were the only designs left standing. In March, 1911, a final torture-test was held, in which both pistols fired 6000 rounds, and then were fed deformed ammunition. The Savage model experienced 37 stoppages, including some caused by broken internal parts. The Browning designed Colt pistol and .45 ACP cartridge performed flawlessly. The choice was clear, and the evaluation committee issued a statement which read, in part, “…the board was of the opinion that the Colt is superior, because it is more reliable, more enduring, more easily disassembled when there are broken parts to be replaced, and more accurate.” On March 28th, 1911, the Colt M1911 and the .45 ACP were adopted as the new sidearm and cartridge of the US Army.


Though replaced as the standard issue sidearm of the US Army in 1985 by the M9 from Beretta, the M1911A1 and its large bore .45 ACP cartridge remains in service to this day, used by the  Marine Corps Special Operations Command as well as Delta force. Numerous law enforcement agencies in the United States rely on the .45 ACP and its more than 100 year history of proven stopping power. The cartridge’s popularity persists within the civilian market as well, with the 1911 arguably being the most esteemed handgun design in the US.

Ordnance manufacturers today offer the .45 ACP in just about any loading configuration that can be imagined. From the traditional and pervasive 230 grain, FMJ or JHP’s, moving at around 800-900 FPS, to the ultra-lightweight, high velocity rounds like Magsafe’s Super Swat 68 grain, 2,200 FPS pre-fragmented hollow point. The overwhelming variety of available loads is a testament to the design’s durability. Like many of Mr. Browning’s creations, the .45 ACP continues to impress more than a hundred years after its conception. Nicely done, John.

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