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 cartridge designed to be used in a semi-automatic pistol with greater ammunition capacity than a revolver. Performance is similar to the 9×23mm Winchester.
Other than specialized competition cartridges like the 9×25mm Dillon (1988), which necked a 10mm Auto case down to a 9mm bullet, the .357 SIG (1994) was the first modern bottleneck commercial handgun cartridge since the early 1960s, when Winchester introduced a .257 caliber round based on the .357 Magnum, the now obsolete .256 Winchester Magnum (1960). Then 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), a shortened version of their .222 Remington. Soon after the .357 SIG, other bottleneck commercial handgun cartridges appeared: the .400 Corbon (1996), necking the .45 ACP down to .40 caliber; the .440 Corbon (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.
The .357 SIG has 1.27 ml (19.5 grains H2O) cartridge case capacity.
.357 SIG maximum C.I.P. cartridge dimensions. All sizes in millimeters.
Americans would define the shoulder angle at alpha/2=18 degrees. The common rifling twist rate for this cartridge is 406 mm (1 in 16 in), 6 grooves, Ø lands=8.71 mm, Ø grooves=9.02 mm, land width=2.69 mm and the primer type is small pistol.
Several sources have published contradicting information regarding .357 SIG headspacing. This is due to the cartridge having been originally designed as a .357 (9.02mm) round, but then rapidly adapted to the .355 (9mm) bullet. According to the official C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portatives) 2008 revised documents, the .357 SIG headspaces on the case mouth (H2). Some US sources are conflict with this standard. However, the cartridge and chamber drawing in the ANSI/SAAMI American National Standards also clearly shows the cartridge headspacing on the cartridge mouth. Likewise, US reloading supplier Lyman has published that the .357 SIG headspaces on the case mouth.
According to the C.I.P. rulings the .357 SIG case can handle up to 305 MPa (44,236 psi) piezo pressure. In C.I.P. regulated countries every pistol cartridge combo has to be proofed at 130% of this maximum C.I.P. pressure to certify for sale to consumers.
The SAAMI pressure limit for the .357 SIG is set at 275.80 MPa (40,000 psi), piezo pressure.
Most .40 S&W pistols can be converted to .357 SIG by replacing the barrel, but sometimes the recoil spring must be changed as well. Pistols with especially strong recoil springs can accept either cartridge with a barrel change. Magazines will freely interchange between the two cartridges in most pistols. .357 SIG barrel kits have allowed this cartridge to gain in popularity among handgun owners. However, the .357 SIG is loaded to higher pressures than the .40 S&W (the C.I.P. and the SAAMI pressure limits for .40 S&W are 225 MPa and 35,000 psi), and may not be suitable for use in all .40 S&W-chambered pistols due to the increase in bolt thrust.
The table below shows common performance parameters for several .357 SIG loads. Bullet weights ranging from 115 to 150 grains (7.5 to 9.7 g) have been offered. Loads are available with energies from 488 foot-pounds force (662 J) to over 568 foot-pounds force (770 J), and penetration depths from 9 inches (230 mm) to over 16.5 inches (420 mm) are available for various applications and risk assessments.
Expansion – expanded bullet diameter (ballistic gelatin).
Penetration – penetration depth (ballistic gelatin).
PC – permanent cavity volume (ballistic gelatin, FBI method).
TSC – temporary stretch cavity volume (ballistic gelatin).
Because of its relatively high velocity for a handgun round, the .357 SIG has an unusually flat trajectory, extending the effective range. However, it does not quite reach the performance of the .357 Magnum with bullets heavier than 125 grains (8.1 g). Offsetting this general slight disadvantage in performance is that semi-automatic pistols tend to carry considerably more ammunition than revolvers.
The Virginia State Police has reported that attacking dogs have been stopped dead in their tracks by a single shot, whereas the former 147 grain 9 mm duty rounds would require multiple shots to incapacitate the animals. Proponents of the hydrostatic shock theory contend that the energy available in the .357 SIG is sufficient for imparting hydrostatic shock with well-designed bullets. Users have commented, "We're really impressed with the stopping power of the .357 SIG round."
The bottleneck shape of the .357 SIG cartridge makes feeding problems almost non-existent. This is because the bullet is channeled through the larger chamber before being seated entirely as the slide goes into full battery. Flat point bullets are seldom used with other autoloader firearms because of feeding problems; however, such bullets are commonly seen in the .357 SIG chambering and are quite reliable, as are hollow-point bullets.
The "Accurate Powder" reloading manual claims that it is "without a doubt the most ballistically consistent handgun cartridge we have ever worked with."
The goal of the .357 SIG project was to offer a level of performance equal to the highly effective 125-grain (8.1 g) .357 Magnum load. The .357 SIG accomplishes this with a 125-grain (8.1 g) bullet at a muzzle velocity of 1,450 feet per second (440 m/s) out of a 4 in (102 mm) barrel, which is generally identical to the velocity achieved by standard factory 125-grain (8.1 g) .357 Magnum loads out of a 4 in (102 mm) revolver barrel.
With a simplistic approach to physics, recoil being directly proportional to "muzzle velocity × bullet mass" (due to conservation of momentum), the recoil of the .357 SIG is equal to or slightly less than that of the .40 S&W, and less than that of the full-power 10mm Auto loads or the original .357 Magnum, Handgun Recoil table as well as Street Stoppers This simple approach to recoil is incomplete since the properties of the bullet alone do not determine the felt recoil, but also the rocket-like blast of propellant gases coming out of the barrel after the bullet leaves the muzzle. A more accurate view on recoil is that it is proportional to the mass of all ejecta × velocity of ejecta. Even so, recoil calculated in this manner is only the starting point in a comparison with the .357 Magnum cartridge, since the latter is used in a revolver, in which the recoil energy is due to the Bullet and propellant less ejecta escaping between the cylinder and breech, while the .357 SIG cartridge is used in a semi-automatic pistol with recoil operation; here, a significant portion of the recoil energy is diverted to cycle the action, effectively prolonging the recoil-phase pulse. Of course, other considerations affect the user's perceived recoil, such as the weight of the weapon, front to back balance, moving mass, height difference between the shooter's grip parallel to the barrel, and grip.
In comparing the energy levels of premium self-defense ammunition, the muzzle energy of 584 ft·lbf (792 J) of the 125 grains (8.1 g) 1,450 feet per second (440 m/s) .357 SIG load is greater than either the 475 ft·lbf (644 J) generated by a 155 grains (10.0 g) 1,175 feet per second (358 m/s) Speer GoldDot .40 S&W load or the 400 ft·lbf (540 J) generated by a 180 grains (12 g) 985 feet per second (300 m/s) Speer GoldDot .40 S&W load.
Like the 10mm Auto, the .357 SIG can be down-loaded to reduce recoil to the point where recoil is similar to that of a 9×19mm Parabellum. However, since the .357 SIG uses bullets that are generally the same as those used in the 9 mm Para, downloading it to this point would defeat the purpose of fielding the SIG cartridge, as the .357 SIG casing was designed to handle up to 160 gr bullets whereas the less-powerful 9mm maxes out at 147 gr bullet weight in subsonic loads.
Because the .357 SIG fires at relatively high pressures, muzzle flash and report can be significant with standard loads, even with longer barrels. Utilizing loads with specialized powders and various bullet weights might reduce flash.
In 1994, Sig released the P229 pistol, the first production handgun introduced that was chambered in .357 SIG and specifically designed to handle the higher pressures of that round.
From 1991 to 1998, the Texas Department of Public Safety (DPS) issued either the SIG Sauer P220 in .45 ACP or the SIG Sauer P226 in 9mm Parabellum at the Trooper's discretion. In 1998, the Texas DPS transitioned to the all-steel, full-sized (34.0 oz) SIG Sauer P226 chambered in the .357 SIG cartridge as the solitary choice of pistol for commissioned officers. In doing so, the Texas DPS became the first government agency to deploy a firearm utilizing the then relatively new .357 SIG chambering.
However, in 2013 the Texas DPS decided to replace their .357 SIG handguns with 9mm handguns. The ability to carry more rounds per magazine (9mm vs. .357 SIG) in a lighter gun were among the stated reasons for the change. That transition was suspended after recruits in the A-2014 class, the first to train with the new S&W M&P 9mm polymer handguns, experienced numerous malfunctions with those weapons.
The newer SIG Sauer P229 in .357 SIG has been adopted for use by agents and officers of the following national and state law enforcement organizations (LEO):United States Secret Service
Federal Air Marshals
Bureau of Industry and Security
Delaware State Police
Montana Highway Patrol
Texas Ranger Division
Virginia State Police
The Tennessee Highway Patrol currently issues the Glock 31 pistol chambered in .357 SIG. The Mississippi Highway Patrol issues the Glock 31 Gen4 in .357 SIG.The Bedford Heights Police Department in Ohio has issued the gen3 Glock 31/32/33 since 2008 and are currently testing gen4 Glock 31s. The Eutawville Police Department in South Carolina issues the Glock 31 in .357 SIG. The Elloree Police Department in South Carolina also issues the Glock 31 in .357 SIG, and the Madison Police Department in Madison, WV issues the Glock 32 in .357 SIG. The Gouverneur Police Department in New York issues the Glock 32. The Lexington Police Department in North Carolina issues the SIG Sauer P229 DAK in .357 SIG. The Oklahoma Highway Patrol and Rhode Island State Police issue the SIG Sauer P226 in .357 SIG. The Paramus Police Department in New Jersey also issues the SIG P229 in .357 SIG. The West Grove Borough Police Department, West Grove PA, also carry the SIG Sauer P229 in the .357 SIG caliber.
Both the New Mexico State Police and the North Carolina State Highway Patrol use SIG Sauer P229s chambered in .357 SIG. The Herculaneum (Missouri) Police Department uses the P229 and P226 in .357 SIG. The Coral Springs Police Department in Florida uses the Sig P226 and P229 Enhanced Elite pistols chambered in .357 SIG. The Orlando Police Department uses the SIG Sauer P229 in .357 SIG. In July 2014 it was announced that the North Carolina State Highway Patrol will equip its 1,600 officers with the SIG Sauer P226 in .357 SIG.