During World War I, the M1917 revolver was created to supplement the 1911 pistol in service. Despite several firearms companies manufacturing the 1911, the US Military was still facing firearms shortages. In response to the shortage, Smith and Wesson quickly produced the M1917 revolver which used the same .45 caliber bullet as the 1911. The .45 is a rimless cartridge designed for use in a magazine fed semi-automatic pistol. Therefore, the M1917 used six round moon clips to load the rounds into the cylinder. This also allowed for easy extraction and faster reloads under stress. The revolver stuck around and served in every war up to and including Vietnam.