Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The .45 Auto Rim is a rimmed cartridge specifically designed to be fired in revolvers originally chambered for the .45 ACP cartridge. Remington-Peters developed the cartridge for use in the M1917 revolver, large amounts of which had become available as surplus following the end of the Great War. The M1917 had previously been used with half-moon clips that held three rounds of the rimless .45ACP. If half-moon or moon clips are not used with a rimless cartridge in a revolver, they must be ejected by hand with a rod or field-expedient tool like a pencil.