The .45 Colt (metric designation: 11.48×35mmR) cartridge is a handgun cartridge dating to 1872. It began as a black-powder revolver round developed for the Colt Single Action Army revolver, but is also offered as a magnum-level, handgun hunting round in modern usage. This cartridge was adopted by the U.S. Army in 1873 and served as an official US military handgun cartridge for 14 years. It is sometimes referred to as .45 Long Colt or .45LC, to differentiate it from the shorter .45 S&W Schofield, as both were used by the Army at the same period of time prior to the adoption of the M1887 Govt.
The .45 Colt was a joint development between Colt’s Patent Firearms Manufacturing Company, of Hartford, Connecticut, and the Union Metallic Cartridge Company of Bridgeport, Conn. Colt began work on the revolver in 1871, and submitted a sample to the U.S. Army in late 1872. The revolver was accepted for purchase in 1873.
The cartridge is an inside lubricated type. The rebated heel type bullet design of its predecessor, the .44 Colt (.452 -.454″ diameter bullet), was eliminated, since it was an outside lubricated type, which would pick up dirt and grit during handling. The .45 Colt replaced the .50 caliber Model 1871 Remington single shot pistol and the various cap-and-ball revolvers converted to take metallic cartridges in use at the time. While the Colt remained popular, the Smith & Wesson M1875 Army Schofield Revolver was approved as an alternate which created a logistic problem for the Army. The S&W revolver used the .45 S&W Schofield, a shorter cartridge, which would also work in the Colt, however the Army’s S&W Schofield revolvers could not chamber the longer .45 Colt, so in the mid 1880’s Frankford Arsenal, then almost exclusive supplier of small arms ammunition to the U.S. Army, dropped production of the .45 Colt in favor of the .45 S&W round. Adoption of the .45 M1887 Military Ball Cartridge resolved the Army’s ammunition logistic problems. The M1887 Govt round was replaced by the .38 Long Colt in 1892. In 1909, the .45 M1909 round was issued along with the Colt New Service revolver. This round was never loaded commercially, and is almost identical to the original Colt round, except having a larger diameter rim. The rim is large enough that it cannot be loaded in adjacent chambers in the rod-ejector Colt model.
The .45 Colt remains popular with renewed interest in Cowboy Action Shooting. Additionally, the round has seen resurgence as a cartridge in handgun hunting and Metallic Silhouette Shooting competitions beginning in the 1950s with the introduction of stronger heavier framed handguns. The cartridge’s popularity has also increased with the introduction of handguns that can also fire the .410 bore shotgun shell, such as the Taurus Judge and the S&W Governor. The modern .45 Colt bullet has changed as well, and it is now .451 inches in diameter for jacketed bullets, and .452 for lead bullets. The .45 Colt became the basis for other rounds, such as the .454 Casull.