Brownells Gun Tech™ and Revolvermeister Steve Ostrem has a special treat for us: a look at the Smith & Wesson Model 1917 revolver in "forty-five" - .45 ACP, that is. When the U.S. entered World War I, the Army's inventory of Colt 1911 pistols - and Colt's capacity to build more quickly enough - was severely limited. As a result, Smith & Wesson chambered their .44 Special Second Model Hand Ejector large-frame revolver in .45 ACP. But that's a rimless semi-auto pistol cartridge, so how do you shoot it in a revolver? The answer is the moon clip (originally a half moon), developed by Joseph Wesson, son of S&W co-founder Daniel Wesson. Other benefits of moon clips are positive ejection of the empties AND super-quick reloads. Later on, Peters Cartridge Co. developed the .45 Auto Rim cartridge - basically a .45 ACP with a rim that's thick enough to fill the gap between the back of the cylinder and the recoil shield. S&W built about 150,000 Model 1917s for the U.S. government, and Colt produced a similar number of their New Service revolver in .45 ACP. In 1937, the government of Brazil ordered 25,000 Model 1917s from Smith, examples of which still show up on the used market today. Later still, Smith & Wesson produced a high-spec commercial model, with nice polished bluing, dubbed the Model 25; the stainless steel version, the Model 625, is still available today.