.357 SIG
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The 357 SIG pistol cartridge is the product of the famous Swiss firearms manufacturer SIG/SAUER, in cooperation with the American ammunition manufacturer Federal Cartridge.
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History
SIGARMS, in partnership with Federal Cartridge, developed the 357 SIG cartridge in 1994. Georg Luger's logic was reversed in the development of this round; the 7.65 mm Luger bottlenecked cartridge evolved into a 9 mm Luger straight-necked cartridge; the 9 mm was then in 1994 placed into a bottlenecked case. The 357 SIG cartridge uses a bottlenecked .40 S&W case crimped to the 9 mm Luger bullet; this is why the 357 sig is not written as ".357", as it is not truly a .357 bullet but instead a standard 9 mm parabellum (.3550"). 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" to generate public interest in the round and to highlight its purpose: to duplicate the performance of the original .357, 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. After the development of the 357 SIG, the .357 Magnum's performance could be harnessed within a small, powerful and concealable automatic package.
Conversions
Any .40 S&W pistol can be converted to 357 SIG, if it is built in a strong enough fashion, by replacing the barrel and (if necessary) recoil spring. Some 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.
Shooting characteristics
The goal of the 357 SIG project was to offer at least the level of performance of the famous .357 Magnum cartridge and +P/+P+ (overpressure and double-overpressure) 9 mm Luger loads. The 357 SIG arguably accomplishes this goal with a 125-grain (8.1 g) bullet. Anything heavier, however, shows the cartridge somewhat inadequate to the original Magnum. The recoil of the 357 SIG cartridge is strong, but not as harsh as full power 10 mm Auto loads or original .357 Magnum. Like the 10 mm auto, the 357 SIG can be down-loaded to reduce recoil, to the point where the "kick" is downgraded similar to that of a 9 mm Luger. Since the 357 SIG uses a standard Luger bullet, downloading it to this point would defeat the purpose of having the SIG cartridge in the first place, at least in terms of stopping power, as recoil AND ballistics would be identical to the lesser Parabellum cartridge.
Flash is definitely noticeable 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; 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
The 357 SIG offers a very flat trajectory like the 10 mm Auto. Combined with expanding bullets, it has very good stopping power. Its drawbacks are its harsh treatment of pistols that are chambered for the cartridge, which have the potential for accelerated wear if not of strong build, and its potential to overpenetrate. The 357 SIG, like the .357 Magnum, is well suited for the use of bullets that can defeat body armor.
The 357 SIG is a good police cartridge; however, it does not quite reach the performance of the venerable .357 Magnum with heavier loads (over 125 gr.) or even with typical commercial loadings in 125 gr. bullets (e.g., a typical commercial .357 Magnum load propels a 125 gr. bullet to 1450 ft/s, while a typical 357 SIG load propels a 125 gr. bullet to 1350 ft/s). Offsetting this slight disadvantage in performance is the fact that pistols carry considerably more ammunition than revolvers. Another disadvantage is that because the 357 SIG uses a .355 bullet at higher velocities than other 9 mm cartridges, very few bullets have been specially designed for it, and the .357 Magnum bullets that are designed for the same velocity range cannot be used due to their diameter. Because of this there are fewer ammunition choices in 357 SIG than one might expect for a .355 caliber cartridge.
This round is excellent when shooting through barricades may prove necessary. There has been a documented case where a police officer's .45 round did not penetrate a tractor's shell but a 357 SIG round from a backup officer's gun did (killing the suspect inside). The forementioned ability of this round to penetrate through barriers is the main reason behind its rapid and growing adoption by federal, state and local law enforcement.
Since the 357 SIG utilizes a standard 9 mm Luger bullet bottlenecked into a .40 S&W (10 mm) case, feeding problems are 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 is the case with hollowpoint ammunition.
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 been corrected with major manufacturers, however, and as a result the SIG round exhibits nominal setback characteristics (similar to other cartridges). For more information read HandGunInfo's website.
Muzzle velocity
There is a large selection of 357 SIG bullet weights available in factory loadings. Generally, the range is from an 87 grain (5.6 g) "screamer" with a velocity of 2000 ft/s (600 m/s) to a high of about 150 grains (9.7 g).
The following data set is based on standard factory loaded cartridges fired from a 4 in (102 mm) barrel chronographed at 20 feet (6 m). This is only a very small sample of what is available.
- 100 grain (6.48 g) Cor-Bon Pow R Ball: 1,703 ft/s (519 m/s)
- 115 grain (7.45 g) Triton BHP : 1,564 ft/s (477 m/s)
- 124 grain (8.04 g) Hornady JHP XTP : 1,329 ft/s (405 m/s)
- 125 grain (8.10 g) Cor-Bon JHP : 1,439 ft/s (439 m/s) --NOMINAL--
- 125 grain (8.10 g) Federal JHP : 1,299 ft/s (396 m/s) --NOMINAL--
- 147 grain (9.53 g) Speer JHP GD : 1,186 ft/s (361 m/s)
- 150 grain (9.72 g) Federal JHP : 1,130 ft/s (344 m/s)
Note: "BHP" stands for "Bonded Hollowpoint" and "JHP" stands for "Jacketed Hollowpoint".
This data was taken from Steve's 357 SIG Ballistic Page.
Implementation
The Sig Sauer P229 in 357 SIG is currently the standard issue firearm carried by agents of the United States Secret Service, Virginia State Police, and various other local and state departments. In most cases, it has replaced 10 mm/.40 S&W and 9mm "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" (Compact)
- Springfield Armory XD 5 in (127 mm) "Tactical" (Full-Size)
- Heckler & Koch USPc (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)
- Walther P99 (with aftermarket barrel)
The manufacture of carbine/bullpup type rifles in this caliber is an interesting concept, as was seen with the 10 mm auto, but an idea yet to be addressed by manufacturers.
Synonyms
- 357 Auto
- 357 Automag