S&W 357 mag.
The .357 Smith & Wesson Magnum, .357 S&W Magnum, .357 Magnum, or 9×33mmR as it is known in unofficial metric designation, is a smokeless powder cartridge with a .357-inch (9.07 mm) bullet diameter. It was created by Elmer Keith, Phillip B. Sharpe,[3] and Douglas B. Wesson[3][4] of firearm manufacturers Smith & Wesson and Winchester.[5][6]