The .357 S&W Magnum (9×33mmR), or simply .357 Magnum, is a revolver cartridge with a .357-inch (9.07 mm) bullet diameter. It was created by Elmer Keith, Phillip B. Sharpe,[5] and D. B. Wesson[5] of firearms manufacturers Smith & Wesson and Winchester.[6][7]
It is based upon Smith & Wesson's earlier .38 Special cartridge. The .357 Magnum cartridge was introduced in 1934, and its use has since become widespread. This cartridge started the "Magnum era" of handgun ammunition.[8]
The .357 Magnum cartridge is notable for its stopping power.