The 45 Auto Rim is a rimmed version of the 45 ACP introduced in 1920 for revolvers chambered for the 45 ACP cartridge. The 1917 Colt revolver in 45 ACP was a World War I accommodation due to inadequate supplies of 1911 pistols. The military used "half moon" clips with 45 ACP cartridges in these revolvers because, if single-loaded, rimless 45 ACP cases must be extracted manually. The 45 Auto Rim solved this problem, and is still manufactured by Cor-Bon. Ballistics are the same as the 45 ACP: 230-grain bullet at 805 feet per second. Many 1917 revolvers are still in use and some modern revolvers have been chambered to 45 ACP and half-moon clips are available...but 45 Auto Rim cartridges and cases are simpler for casual shooting.
