The .357 Smith & Wesson Magnum, .357 S&W Magnum, .357 Magnum, or 9×33mmR is a smokeless powder cartridge with a 0.357 in bullet diameter. It was created by Elmer Keith, Phillip B. Sharpe, and Douglas B. Wesson of firearm manufacturers Smith & Wesson and Winchester. The .357 Magnum cartridge is notable for its highly effective terminal ballistics.
The .357 Magnum cartridge is based upon Smith & Wesson's earlier .38 Special cartridge. It was introduced in 1935, and its use has since become widespread. From Wikipedia
