357 SIG Ammunition

357 SIG Ammo: Specifications, Performance, and Brands

357 SIG ammo is a bottlenecked rimless centerfire handgun cartridge that fires a 9.02 mm (0.355 in) bullet at 1,350-1,900 ft/s (410-580 m/s). SIGARMS (now SIG Sauer) developed the cartridge in 1994 with Federal Premium Ammunition. This guide covers cartridge specifications, history, performance data, comparisons with other calibers, barrel conversions, law enforcement use, and loads from 15 ammunition brands with price per round.

What Is 357 SIG Ammo?

357 SIG ammo is a necked-down 10mm Auto case that holds a 9 mm bullet and a small pistol primer. The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) designates the cartridge 357 Sig. The Commission Internationale Permanente (C.I.P.) designates it 357 SIG, and the metric name is 9×22 mm.

Cartridge Specifications

The cartridge measures 28.97 mm (1.141 in) in overall length (OAL) with a 21.97 mm (0.865 in) case. Each specification below applies to factory 357 SIG ammo.

• Bullet diameter: 9.02 mm (0.355 in)
• Case length: 21.97 mm (0.865 in)
• Overall length (OAL): 28.97 mm (1.141 in)
• Case capacity: 1.27 cm³ (19.6 gr H₂O)
• Rifling twist: 406 mm (1 in 16 in)
• Maximum pressure, SAAMI: 275.8 MPa (40,000 psi)
• Maximum pressure, C.I.P.: 305.0 MPa (44,240 psi)
• Primer: small pistol

Bullet Weights

Bullet weights range from 50 gr (3.2 g) to 150 gr (9.7 g). Liberty loads the lightest bullet, and Federal and Hornady load the heaviest. Most 357 SIG ammo uses 115-147 gr (7.5-9.5 g) bullets.

History of the 357 SIG Cartridge

SIGARMS (now SIG Sauer) introduced the 357 SIG in 1994 to match the 125 gr .357 Magnum load in a semi-automatic pistol. Federal Premium Ammunition cooperated on the design. The SIG P229 was the first production pistol chambered in the cartridge.

Design Goals

The design goal was .357 Magnum terminal performance from a magazine-fed pistol. A revolver holds 6-8 rounds, and a semi-automatic pistol in 357 SIG holds 12-15 rounds. The bottleneck case shape also makes feeding problems almost non-existent.

Market Position

The 357 SIG was the first modern bottlenecked commercial handgun cartridge since the .256 Winchester Magnum (1961). The cartridge costs about 2 times as much as 9mm, which limits widespread adoption. Law enforcement agencies and handgun hunters form most of the demand.

357 SIG Ammo Performance

Factory 357 SIG ammo produces 506-721 ft·lbf (686-978 J) of muzzle energy with 90-125 gr bullets. The high velocity gives the cartridge an unusually flat trajectory for a handgun round. The table values below come from ballistic gelatin testing.

Velocity and Energy Data

The 90 gr Grizzly JHP is the fastest load at 1,900 ft/s (580 m/s) and 721 ft·lbf (978 J). The 125 gr Underwood Gold Dot JHP follows at 1,450 ft/s (442 m/s) and 583 ft·lbf (790 J). The remaining common loads are listed below.

• 125 gr (8.1 g) Federal FMJ: 1,350 ft/s (410 m/s), 506 ft·lbf (686 J)
• 125 gr (8.1 g) Speer Gold Dot JHP: 1,385 ft/s (422 m/s), 532 ft·lbf (721 J)
• 125 gr (8.1 g) Underwood Gold Dot JHP: 1,450 ft/s (442 m/s), 583 ft·lbf (790 J)
• 125 gr (8.1 g) Winchester Ranger T: 1,385 ft/s (422 m/s), 532 ft·lbf (721 J)
• 90 gr (5.8 g) Grizzly JHP: 1,900 ft/s (580 m/s), 721 ft·lbf (978 J)

Expansion and Penetration

The 125 gr Speer Gold Dot JHP expands to 0.68 in (17.3 mm) and penetrates 16.5 in (419 mm) of ballistic gelatin. The 125 gr Winchester Ranger T expands to 0.75 in (19.1 mm). Both loads exceed the 12 in (305 mm) minimum penetration depth commonly used for handgun duty ammunition.

357 SIG Compared With Other Calibers

357 SIG delivers more velocity and energy than 9mm and .40 S&W, and nearly the same velocity as .357 Magnum. The cartridge costs more per round than 9mm and .40 S&W. Each comparison below uses factory ammunition.

357 SIG vs .357 Magnum

357 SIG and .357 Magnum produce nearly identical velocity with 125 gr bullets from a 4 in (102 mm) barrel. The .357 Magnum fires a 9.07 mm (0.357 in) bullet from a revolver, and the 357 SIG fires a 9.02 mm (0.355 in) bullet from a semi-automatic pistol. The semi-automatic platform carries more rounds per magazine.

357 SIG vs .40 S&W

357 SIG produces 584 ft·lbf (792 J) of muzzle energy, and 155 gr .40 S&W produces 475 ft·lbf (644 J). Recoil from 357 SIG equals or slightly trails .40 S&W recoil. Both cartridges share the same pistol frames in most models.

357 SIG vs 9mm

357 SIG delivers higher velocity and more energy than 9mm at about 2 times the cost per round. The 9mm Luger remains the lower-cost choice for high-volume training. The 357 SIG suits shooters who prioritize velocity, barrier performance, and a flat trajectory.

Converting Pistols to 357 SIG

Most .40 S&W pistols convert to 357 SIG with a barrel swap. The case length differs by only 0.009-0.020 in (0.23-0.51 mm) between the two cartridges. Some pistols need a different recoil spring.

Magazines and Recoil Springs

Magazines interchange between .40 S&W and 357 SIG in most pistols. A recoil spring change is sometimes required because 357 SIG generates higher slide velocity. Check the manufacturer's specification for each model before firing.

Threaded and Conversion Barrels

A 357 SIG barrel installs in the same frame as the original barrel, and the slide, frame, and magazines stay in place. Owners who also shoot 9mm often pair a conversion barrel with SIG P320 threaded barrels for suppressor-ready setups. Compact-frame owners can compare P365 threaded barrels in the same way. Owners of smaller SIG pistols can also review SIG P238 accessories for holsters and magazines.

Law Enforcement Use of 357 SIG

Federal Air Marshals, Virginia State Police, Delaware State Police, Texas Rangers, Rhode Island State Police, and the U.S. Secret Service (before 2019) carried 357 SIG. Agencies selected the cartridge for barrier performance and high velocity. Virginia State Police reported single-shot stops on attacking dogs where 147 gr 9mm required multiple shots.

357 SIG Ammo Brands and Loads

Fifteen brands load 357 SIG ammo, with prices from $0.51 to $1.75 per round. Prices vary by retailer and lot, and the figures below are approximate. Each brand lists its loads by bullet weight and type.

Training and Range Ammo

Full metal jacket (FMJ) and total metal jacket (TMJ) loads cost $0.51-$0.90 per round. Ammo Inc 124 gr TMC is the lowest at $0.51. These loads suit range practice and function testing.

Speer

Speer loads Gold Dot 125 gr JHP at $0.70-$0.90 per round. Lawman 125 gr TMJ costs $0.525 per round for training. Lawman RHT 100 gr Frangible TMJ serves steel-range and indoor use.

Winchester

Winchester loads USA 125 gr FMJ at $0.611 per round. Ranger T 125 gr JHP is a duty load. Defender PDX1 125 gr Bonded JHP costs $1.50 per round.

Remington

Remington loads UMC 125 gr FMJ at $0.90 per round. Golden Saber 125 gr Bonded JHP costs $1.486 per round. Both loads use a 125 gr (8.1 g) bullet.

Federal

Federal loads HST 125 gr JHP at $0.96 per round for law enforcement and $1.75 per round at retail. American Eagle 125 gr FMJ costs $0.60 per round. Hydra-Shok 125 gr JHP is a second defensive option.

Hornady

Hornady loads Custom 147 gr XTP JHP at $1.20 per round. Critical Duty 135 gr FlexLock costs $1.60 per round. Both loads use heavier bullets than the 125 gr standard.

Underwood

Underwood loads 115 gr, 124 gr, and 147 gr JHP at about $1.10 per round each. The 125 gr Gold Dot version reaches 1,450 ft/s (442 m/s). Underwood loads run at higher velocity than most factory ammunition.

Sellier & Bellot

Sellier & Bellot loads 140 gr FMJ at $0.65 per round and 124 gr JHP at $0.67 per round. Both loads are among the lower-cost imports. The 140 gr FMJ suits training.

SBR

SBR loads 125 gr JHP at $0.842 per round. The 130 gr FMJ TCJ costs $0.60 per round. TCJ stands for total copper jacket.

Geco

Geco loads a 100 gr frangible NTF/Super Matrix bullet. Frangible bullets disintegrate on steel and hard targets. Ranges that restrict lead and ricochet use this load.

Liberty

Liberty loads a 50 gr fragmenting lead-free hollow point at $1.55 per round. The 50 gr (3.2 g) bullet is the lightest 357 SIG bullet. Light bullets reach very high velocity.

Ammo Inc

Ammo Inc loads 124 gr TMC at $0.51 per round. TMC stands for total metal case. The load is the lowest-cost 357 SIG ammo listed here.

Prvi Partizan

Prvi Partizan loads 125 gr FMJ-FP at $0.60 per round. FMJ-FP stands for full metal jacket flat point. The load targets range practice.

CCI/ProGrade

CCI/ProGrade loads 125 gr Barnes TAC-XP at $0.90 per round. The Barnes TAC-XP is a solid copper hollow point. Solid copper bullets retain weight through barriers.

CorBon

CorBon loads 125 gr JHP at $1.30 per round. The load targets defensive use. CorBon ammunition runs at higher pressure than standard loads within SAAMI limits.

Grizzly

Grizzly loads a 90 gr JHP at $1.30 per round and 1,900 ft/s (580 m/s). The load produces 721 ft·lbf (978 J) of muzzle energy. The load is the fastest factory 357 SIG ammo listed here.