 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 center fire 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
.357 SIG compared to 9mm
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. |