The .357 Sig was an attempt by the engineers at SIG arms to create an autoloading pistol round that reproduced the ballistic characteristics of the venerable .357 Magnum. Their success or failure in this regard is still debateable.

The .357 Sig is not a true .357 as it does not use a .357" bullet, rather it uses a .355" (aka 9mm) bullet in a .40 S&W case necked down to accomodate the smaller bullet.

While it does generate higher velocities than an ordinary 9mmx19 it is usually a hundred or so fps below true .357 Magnum velocities. It is quite safe to say, if you want magnum performance then use a magnum revolver and fire magnum rounds. Although to be fair, the improvement of muzzle velocity in the .357 Sig is considerable and if not for the higher price and less availability it could just as easily have been as popular as the 9mm.

D.E. Watters could not have said it better when he said that "one might wonder if the .357 Sig would be as popular as it is if it were named the 9x22 Sig."(9mmx22 would be it's designation in standard NATO measurement nomenclature)

Come to think of it, maybe it wasn't the engineers that made this round, sounds more like the work of the marketroids.

The problem with .357 Sig ammuntion is that it is not usually reloadable. Because the .357 Sig is really a .40 S&W necked down to hold a 9mm projectile, if the reloader puts the bullet 1/100th of an inch too far in, the pressure when firing exceeds fail levels.

In other ways, the .357 Sig is everything that the 9mm and .45 or .40 aren't. It is faster than the +P 9mm loads, and has better terminal ballistics than the heavier .45ACP .

Cor Bon is the premier manufacturer of quality .357 Sig ammo, and produces two different loads. The 115 grain, 1500 FPS that hits with 575 ft/lbs of energy, and the 125 grain, 1425 FPS that impacts at 564 ft/lbs. This, in comparison to the 9mm is excellent performance. The fastest and most powerful +P 9mm loads only manages to reach 466 ft/lbs. .357 Sig even out performs the venerable .45ACP and newer .40 Smith and Wesson. The classic .45 +P load made by Cor Bon is close at 573 ft/lbs, but will have more recoil due to the 165 grain bullet. By comparison, the .40S&W only develops 526 ft/lbs from its highest load.

A side note, NEVER overload or purchase +P .40S&W ammo. It DOES NOT exist. .40 pistols were never designed for higher pressures, and will fail.

The only autoloading handgun cartridge that surpasses the .357 Sig is the 10mm auto that belts out a whopping 647 ft/lbs of muzzle energy. Keep in mind that you will be feeling that through your wrist. The 10mm kicks like a big bore magnum revolver.

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