.357 Magnum

Test barrel length: 4 in (102 mm) (vented)
Sources: Federal,

The .357 Smith & Wesson Magnum, .357 S&W Magnum, .357 Magnum, or 9×33mmR is a rimmed, smokeless powdercartridge with a 0.357 in (9.07 mm) 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 a magnum cartridge based on Smith & Wesson's earlier .38 Special cartridge. It was introduced in 1935 and has seen widespread use.