The .45 Colt: A 19th-century revolver cartridge that refuses to retire

Wars & Conflicts · Published 15 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: Developed in 1872 for the iconic Colt Single Action Army, the .45 Colt remains a staple of modern shooting. While it once faced logistical nightmares and military replacement, this versatile round has evolved from a black-powder man-stopper into a powerful hunting cartridge used in everything from derringers to lever-action rifles.

The .45 Colt was born from a collaboration between Colt’s Patent Firearms Manufacturing Company and the Union Metallic Cartridge Company. Submitted to the U.S. Army in 1872 and adopted in 1873, it was designed as a powerful, inside-lubricated cartridge to replace the unreliable, dirt-attracting outside-lubricated bullets of the era. Its reputation as a formidable man-stopper and horse-killer was cemented by its original load: a 255-grain lead bullet propelled by 40 grains of black powder. However, this potent combination proved too much for the average soldier, leading the Army to eventually reduce the powder charge.

The cartridge’s history is marked by logistical friction. When the Army adopted the Smith & Wesson M1875 Schofield, which used a shorter .45 Schofield cartridge, it created a supply crisis. The Schofield could fire the longer .45 Colt, but the Colt revolvers could not chamber the shorter Schofield rounds. To simplify logistics, the Army briefly issued a .45 Colt Government cartridge—a hybrid with a shorter case and reduced powder charge—that could function in both weapons. By 1892, the military officially replaced the .45 Colt with the .38 Long Colt, though it saw a brief resurgence during the Philippine-American War.

Today, the .45 Colt enjoys a second life, far exceeding its original design parameters. While standard factory loads are roughly equivalent to the .45 ACP, modern handloaders and manufacturers have pushed the cartridge into the same performance class as the .44 Magnum. These high-pressure loads are restricted to robust, large-frame revolvers like the Ruger Blackhawk and specific lever-action rifles. Because of its historical significance and versatility, the cartridge remains a favorite in Cowboy Action Shooting and as a hunting round for deer and black bear, proving that a design from the 1870s can still hold its own in the modern era.

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