300px-357 SIG - FMJ - SB - 1
.357 SIG
Country of origin

United States of America




Federal Cartridge Co.

Year(s) designed


Parent cartridge

10mm Auto

Overall length

28.96 mm (1.140 in)

Case length

21.97 mm (0.865 in)

Neck diameter

9.68 mm (0.381 in)

Shoulder diameter

10.77 mm (0.424 in)

Base diameter

10.77 mm (0.424 in)

Rim diameter

10.77 mm (0.424 in)

Rim thickness

1.40 mm (0.055 in)

Rifling twist

406 mm (1 in 16 in)

Muzzle velocity

1350 fps to 1600 fps

Primer type

Small pistol

Used by

United States of America

The .357 SIG (9×21mm in metric) is a pistol cartridge, designed by the Swiss firearms company SIG-Sauer.

Design detailsEdit

It is based on a .40 S&W case necked down to accept 0.355-inch (9.0 mm) bullets; the .357 SIG brass is slightly longer (0.009-inch (0.23 mm) to 0.020-inch (0.51 mm)). The cartridge is used by a number of law enforcement agencies and has a good reputation for both accuracy and stopping power.

Developed in 1994, the new cartridge was named ".357" to highlight its purpose: to duplicate the performance of 125-grain (8.1 g) .357 Magnum loads fired from 4-inch (100 mm) barreled revolvers in a pistol cartridge. Performance is similar to the 9×23mm Winchester.

The .357 SIG provided a self-defense cartridge close in performance to a 125 gr .357 Magnum, but from a semi-automatic pistol with greater ammunition capacity.

Other than specialized competition cartridges like the 9×25mm Dillon (1988), necking a 10mm Auto case down to a 9mm bullet, the .357 SIG was the first modern bottleneck commercial handgun cartridge since the early 1960s, when Remington introduced the unsuccessful .22 Remington Jet (1961), which necked a .357 Magnum case down to a .22 caliber bullet, and the .221 Remington Fireball (1963). Soon after the .357 SIG, other bottleneck commercial handgun cartridges appeared: the .400 Cor-Bon (1997), necking the .45 ACP down to .40 caliber; the .440 Cor-Bon (1998), necking down the .50 AE to .44 caliber; the .32 NAA (2002), necking the .380 ACP down to .32 caliber; and the .25 NAA (2004), necking the .32 ACP down to .25 caliber.