.357 SIG
| 357 SIG | ||||||||||||||||||||||||
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 .357 SIG (third from left) in comparison with other cartridges | ||||||||||||||||||||||||
| Type | Pistol | |||||||||||||||||||||||
| Place of origin | United States | |||||||||||||||||||||||
| Production history | ||||||||||||||||||||||||
| Designer | SIGARMS/Federal Cartridge Co. | |||||||||||||||||||||||
| Specifications | ||||||||||||||||||||||||
| Case type | Rimless, bottleneck | |||||||||||||||||||||||
| Bullet diameter | .355 in (9.0 mm) | |||||||||||||||||||||||
| Neck diameter | .381 in (9.7 mm) | |||||||||||||||||||||||
| Shoulder diameter | .424 in (10.8 mm) | |||||||||||||||||||||||
| Base diameter | .424 in (10.8 mm) | |||||||||||||||||||||||
| Rim diameter | .424 in (10.8 mm) | |||||||||||||||||||||||
| Rim thickness | .055 in (1.4 mm) | |||||||||||||||||||||||
| Case length | .865 in (22.0 mm) | |||||||||||||||||||||||
| Overall length | 1.14 in (29 mm) | |||||||||||||||||||||||
| Primer type | Small pistol | |||||||||||||||||||||||
| Ballistic performance | ||||||||||||||||||||||||
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| Test barrel length: 4 in Source(s): Steve's 357 SIG Ballistic Page | ||||||||||||||||||||||||
The 357 SIG pistol cartridge is the product of Swiss firearms manufacturer SIG-Sauer, in cooperation with the American ammunition manufacturer Federal Cartridge.
History
SIGARMS, in partnership with Federal Cartridge, developed the 357 SIG cartridge in 1994. Contrary to popular belief, the 357 SIG cartridge is not a .40 S&W case necked down to accept .355 inch bullets. Forming brass for the 357 SIG in this way is dangerous, leading to case ruptures due to generated pressures much higher than those the .40 S&W case was designed for. Instead the 357 SIG round uses thicker brass than the .40 S&W casing to cope with the higher pressures caused by the neck of the casing. Allegedly, SIG shied away from calling its new cartridge a nine-millimeter-anything for fear of public rejection of the round. Instead, it was dubbed a "357" in order to highlight its purpose: to duplicate the performance of 125-grain .357 Magnum loads fired from 4-inch barrelled revolvers, except in a cartridge designed to be used expressly in an autoloader platform.
Until the 357 SIG, few autoloaders were chambered for .357 Magnum: the Desert Eagle and rare Coonan, for example. This is due to the difficulty of designing a reliable autoloading handgun that can store and feed the rimmed .357 Magnum cartridge, which itself is much longer than most common autopistol cartidges. Nearly every autofeed centrefire pistol cartridge is "rimless", i.e. has a rebated rim that the extractor engages unlike revolver cartridges such as the .357 Magnum. After the development of the 357 SIG, the .357 Magnum's performance could be harnessed within a small, powerful and concealable automatic package.
Conversions
Most .40 S&W pistols can be converted to 357 SIG by replacing the barrel, and sometimes the recoil spring. Pistols with especially strong recoil springs can accept either cartridge with a barrel change only. Magazines will freely interchange between the two cartridges. 357 SIG barrel kits have allowed this cartridge to continue to gain in popularity among handgun owners. However, the 357 SIG is loaded to higher pressures than the .40 S&W (a difference of up to 5,000 psi at top loads), and may not be suitable for use in all .40 S&W-chambered pistols.
Shooting characteristics
The goal of the 357 SIG project was to offer at least the level of performance of lighter .357 Magnum loads and +P/+P+ 9 mm Luger loads. The 357 SIG accomplishes this goal with a 125-grain (8.1 g) bullet. Using heavier bullets, however, shows the cartridge somewhat inferior to the original Magnum. The recoil of the 357 SIG cartridge is strong, often noticeably more so than the .40 S&W, but is not as harsh as full-power 10 mm Auto loads or the original .357 Magnum.
Like the 10 mm Auto, the 357 SIG can be down-loaded to reduce recoil, to the point where recoil is similar to that of a 9 mm Luger. However, since the 357 SIG uses bullets that are generally the same as those used in the 9 mm Luger,[1] downloading it to this point would defeat the purpose of having the SIG cartridge in the first place, as recoil and ballistics would be identical to the less-powerful 9 mm Luger cartridge.
Because the 357 SIG fires at relatively high pressures, both muzzle flash and noise are significant with standard loads, even when using longer barrels. Utilizing loads with specialized powders to reduce flash and experimenting with different bullet weights can rein flash levels to within desirable limits.
Handloading
Because the 357 SIG is based on the .40 S&W case, novice handloaders may be tempted to form .40 S&W cases into 357 SIG brass. This must not be done. Although the two cases are identical in rim diameter, using the .40 S&W case to form 357 SIG cases will result in a case that is approximately 0.020 in (0.508 mm) too short. Unlike most bottlenecked cartridges, the 357 SIG headspaces on the case mouth;[1] cartridges that are too short can result in serious malfunctions of the guns in which they are used, possibly leading to serious injury. Furthermore, the SAAMI limit for the .40 cartridge is set at 35,000 psi, but at 40,000 psi for the 357 SIG.
While some individuals have attempted to form 357 SIG cases from 10 mm cases, this is rather impractical. First of all, the change in primer type (10 mm uses large pistol primers, 357 SIG uses small pistol primers) would require that known recipes be scrapped, and second, the cost of using expensive 10 mm brass for such a purpose would certainly defeat the goal of saving money by reloading. Both unfired and once-fired 357 SIG brass are readily available from several well-known vendors, at a low cost.
Choosing the correct bullet type is extremely important when handloading the 357 SIG cartridge. The short neck of the casing makes the use of standard round-nosed bullets impractical. There is simply not enough flat area for the neck to "grip" the bullet. For this reason, flat point bullets are used instead. Various 9 mm hollowpoint bullets can also be successfully used, but due to the wide variety of choices out there, the chances of success vary from one brand/model to another.
Performance
Because of its relatively high velocity for a handgun round, the 357 SIG offers a very flat trajectory, which in turn allows the firearms chambered for it a bit more effective range over those chambered for its contemporaries. However, it does not quite reach the performance of the venerable .357 Magnum with bullets heavier than 125 grains, or with typical commercial loadings using 125-grain bullets (e.g., fired from a four-inch barrel, a typical commercial .357 Magnum load propels a 125-grain bullet to 1450 ft/s, while a typical 357 SIG load propels the same bullet to 1350 ft/s). Specialty loads, such as Double Tap Ammunition, are able to propel a 125-grain bullet to 1450 ft/s from a four-inch barrel. Offsetting this general slight disadvantage in performance is the fact that semi-automatic pistols tend to carry considerably more ammunition than revolvers.
However, this comparatively high velocity can also create the potential for overpenetration. The 357 SIG, much like the .357 Magnum and the similarly necked 7.62 Tokarev, is well-suited for use with bullets that are designed to defeat body armor. Also like the Tokarev, the 357 SIG works well when shooting through barricades is necessary. There has been a documented case in Texas where a police officer's .45 round did not penetrate a tractor-trailer's shell, but a 357 SIG round from a backup officer's gun did (killing the suspect inside).[2] The round's ability to penetrate barriers is the main reason for its adoption by law enforcement agencies.
The myth that the 357 SIG round loses its crimp (allowing for bullet setback) was partially true when the cartridge was new and ammunition manufacturers were just beginning to produce the round. These problems have since been corrected by major manufacturers. As a result, the SIG round now exhibits nominal setback characteristics (similar to other cartridges).
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 platforms because of feeding problems; however, such bullets are commonly seen in the 357 SIG chambering and are quite reliable, as are hollowpoint bullets.
One disadvantage of the 357 SIG is that it fires a .355" bullet at higher velocities than most bullets of the caliber are designed for. Very few bullets have been designed specifically for the 357 SIG, and .357 Magnum bullets that are designed for the same velocity range cannot be used due to their slightly larger diameter. Because of this, there are fewer ammunition choices in 357 SIG than one might expect for a cartridge using .355" bullets.
Another drawback of the 357 SIG is its often harsh treatment of the pistols that are chambered for it. Many are designed to fire the .40 S&W and are later modified for use with the 357 SIG. Firing regularly at pressure levels effectively beyond what the pistol was originally engineered for tends to translate to accelerated wear on the firearm.
Implementation
The SIG-Sauer P229 in 357 SIG is currently the standard issue firearm carried by agents of the United States Secret Service, officers of the Federal Protective Service, the North Carolina State Highway Patrol, Virginia State Police, Tennessee Highway Patrol - Glock 31, Federal Air Marshals, and various other local and state departments. In most cases, it has replaced 10 mm/.40 S&W and 9 mm "Para" loads. In 1995, the Texas Department of Public Safety became the first government agency to implement the 357 SIG.
Platforms
Firearms being or having been produced for the 357 SIG cartridge number many. Here are a few in production as of the year 2005:
- Glock 31 (Full-Size)
- Glock 32 (Compact)
- Glock 33 (Sub-Compact)
- SIG P226/P226R DAK (Full-Size)
- SIG P229 (Compact)
- SIG P239 (Sub-Compact)
- SIG SP2340 (Polymer Compact)
- SIG SP2022 (Polymer Compact)
- Springfield Armory XD 4 in (102 mm) "Service"
- Springfield Armory XD 5 in (127 mm) "Tactical"
- Heckler & Koch USP Compact (Compact)
- Heckler & Koch P2000 (Compact)
- Heckler & Koch P2000SK (Sub-Compact)
- Steyr M357 A-1 (Full-Size, Polymer with reinforced Steel frame)
- Smith & Wesson M&P (Full-Size and Compact)
- Walther P99 (Full-Size) (note: Walther never produced the P99 in the 357 sig. However, via a replacement barrel, the 40 cal version could be easily converted)
- Kel-Tec P-40 (with aftermarket barrel)
- Vector Arms HK style carbines, pistols, and rifles (referred to as SP98 and SP98k in its pistol variant)
The manufacture of carbine/bullpup type rifles in this caliber is an often-discussed concept that has yet to be addressed by major manufacturers. To date, the only manufacturer offering 357SIG carbines and rifles is Vector Arms, with its selection of HK style weapons.
Synonyms
- .357 Auto (Uncommon; not to be confused with .357 Auto Mag, an entirely different cartridge. .357 Auto is rollmarked on Glock pistols.)