The .357 S&W Magnum (9×33mmR), or simply .357 Magnum, is a revolver cartridge with a .357-inch (9.07 mm) bullet diameter, created by Elmer Keith, Phillip B. Sharpe, and Colonel D. B. Wesson of firearms manufacturer Smith & Wesson, and Winchester. 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. The .357 Magnum cartridge has a positive reputation for stopping power.