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.