This was a development by Peters Cartridge Company around 5 years after the introduction of the 45 ACP as an effective alternative to the use of half-moon clips on the 45 ACP cartridges in the S&W and Colt Model 1917 Revolver. There was a large number of surplus revolvers on the market post World War 1 and although the clip system worked well for the Army where rounds came fitted with clips holding 3 rounds, the system proved impractical for the civilian market. Problems encountered were of clips varying in size as well as quality which prompted Peters to launch a 45 ACP with a rim. The rim is about 50% thicker than rims for the 45 Colt in order to compensate for the rim as well as the clip which is no longer necessary. (Erlmeier, Brandt Ref. 429).