.357 SIG
.357 SIG was designed to duplicate the legendary .357 Magnum's performance in a semi-auto pistol. It necks a .40 S&W case down to accept a 9mm-diameter bullet, driving it at high velocity for a flat trajectory, deep penetration and a sharp report. Adopted by several federal and state law-enforcement agencies, it's a serious defensive cartridge.
Why the .357 SIG
The appeal is velocity: typical 125gr JHP loads leave the muzzle fast, giving reliable expansion, flat shooting and excellent barrier performance — the reason agencies chose it. The bottleneck case also feeds very reliably. In exchange you get more muzzle blast, more recoil and higher ammo cost than 9mm.
Range & defense
FMJ practice loads keep training going, while premium JHP loads (Speer Gold Dot, Federal HST) are the defensive choice. Because it's a lower-volume cartridge, buy ahead when you find it in stock.
Brands & bulk
We stock Speer, Federal, Winchester and Magtech in FMJ and JHP. Compare other handgun ammo calibers or browse all ammunition at Specialty Sports & Supply.
Before you buy: federal law sets a minimum age of 21 to purchase handgun ammunition — check your state and local laws. See the ATF for federal guidance.
Frequently asked questions
What is .357 SIG good for?
Self-defense and duty use — it delivers high velocity, reliable expansion and strong barrier performance in a semi-auto.
Is .357 SIG the same as .357 Magnum?
No — .357 SIG is a semi-auto pistol cartridge designed to mimic .357 Magnum ballistics; the Magnum is a revolver round. They're not interchangeable.
Why do police use .357 SIG?
For its flat trajectory, reliable feeding and excellent performance through barriers like auto glass.
Does .357 SIG have a lot of recoil?
It's snappier and louder than 9mm, with a sharp muzzle blast, though many shooters manage it well with practice.
How much does .357 SIG cost?
More than 9mm — typically $0.50–$1.00+ per round depending on FMJ vs. premium JHP.