A little Trivia for ya.
The .45 Colt cartridge (also referred to, incorrectly, as the .45 Long Colt) was developed by the US Army at Frankford Arsenal in 1872 as an improvement of the British .476 Eley to replace the standard issue Smith and Wesson .44 round (which was shorter) in the famous Colt Single Action Army, often known as the Peacemaker single action revolver. The US Army adopted the cartridge in 1873 and it remained in use until 1877 when the army went to the M1877 ball revolver load. The new round was shorter than the original in case length and used a reduced powder charge of approximately 30 grains (1.9 g) of black powder vs the 40 grains (2.6 g) in the original. All Colt army revolvers were still chambered to fit the longer .45 cartridge case. In 1892 it was replaced by the .38 Long Colt. The US Army briefly reintroduced the .45 Colt in 1902 for use in the Philippines, but it was made obsolete by new automatic pistols firing .45 ACP.