The M1917 Revolvers were six-shot, .45 ACP, large frame double action revolvers adopted by the United States Military in 1917, to supplement the standard M1911 pistol during World War I. There were two variations of the M1917, one made by Colt and the other by Smith & Wesson. They used moon-clips to hold the cartridges in position, facilitate reloading, and to aid in extraction since revolvers had been designed to eject rimmed cartridges and .45 ACP rounds were rimless for use with the magazine-fed M1911. After World War I, they gained a strong following among civilian shooters. A commercial rimmed cartridge, the .45 Auto Rim, was also developed, so M1917 revolvers could eject cartridge cases without using moon-clips.

Colt's Manufacturing Company, LLC is an American firearms manufacturer, founded in 1855 by Samuel Colt and now a subsidiary of Czech holding company Colt CZ Group. It is the successor corporation to Colt's earlier firearms-making efforts, which started in 1836. Colt is known for the engineering, production, and marketing of firearms, most especially between the 1850s and World War I, when it was a dominating force in its industry and a seminal influence on manufacturing technology. Colt's earliest designs played a major role in the popularization of the revolver and the shift away from single-shot pistols. Although Samuel Colt did not invent the revolver concept, his designs resulted in the first very successful model.