357 Sig ammo

357 SIG ammo is the bottlenecked semi-auto cartridge built to do one thing: replicate the legendary stopping power of the .357 Magnum in a high-capacity, flat-shooting pistol. Developed by SIG Sauer and Federal in 1994 by necking down a .40 case to a .355-inch bullet, the .357 SIG drives a 125-grain bullet around 1,350 fps — fast, flat, and hard-hitting. It earned a strong following among federal agencies and shooters who want magnum-style velocity in a duty pistol. This page covers what makes it distinct and how it compares.

Tatted Tacticals stocks .357 SIG from Federal, Speer, Underwood, and Sig Sauer — FMJ practice and bonded defensive hollow points, in boxes and bulk.

What Makes the .357 SIG Different

The bottleneck case is the giveaway: necking a .40-caliber case down to a 9mm bullet lets the .357 SIG push light bullets very fast, mimicking a 125-grain .357 Magnum revolver load from a semi-auto. The result is a flat trajectory, excellent feeding reliability from the bottleneck shape, and snappy recoil with a distinct report. It delivers more energy than standard 9mm at the cost of more recoil, muzzle blast, and higher ammo price. Our .357 SIG ballistic data shows the numbers.

.357 SIG vs. 9mm and .357 Magnum

Two comparisons come up constantly. Versus 9mm, the .357 SIG hits harder and shoots flatter but costs more and recoils more in a lower-capacity package. Versus the .357 Magnum revolver cartridge it’s named after, it is a different, shorter cartridge that approximates the magnum’s 125-grain ballistics in an autoloader — they are not interchangeable. Shooters cross-shopping auto power also look at .40 S&W (its parent case), 10mm, and .45 ACP. Standards follow SAAMI specifications.

Buying .357 SIG

As a lower-volume cartridge, .357 SIG is pricier and less common than 9mm or .40, so buying in bulk when available makes sense. Federal law sets the minimum age for handgun ammunition at 21, and some states restrict online sales; per ATF guidance, confirm federal rules, then review our ammunition shipping rules and state restrictions before ordering.

.357 SIG Ammo — Frequently Asked Questions

Are .357 SIG and .357 Magnum the same?

No. They share a goal — 125-grain bullet at high velocity — but are entirely different cartridges. The .357 Magnum is a longer rimmed revolver round; the .357 SIG is a shorter bottlenecked semi-auto cartridge based on the .40 S&W case. They are not interchangeable, though the SIG was designed to approximate the magnum’s ballistics in a pistol.

Is .357 SIG more powerful than 9mm?

Yes. The .357 SIG drives a 125-grain bullet faster than standard 9mm, producing more energy and a flatter trajectory. The trade-offs are sharper recoil, louder muzzle blast, lower magazine capacity, and higher ammo cost. For shooters who want magnum-style velocity in a semi-auto, that’s the appeal.

Is .357 SIG ammo still made?

Yes. While it never reached the popularity of 9mm and some agencies have moved away from it, .357 SIG remains in production from Federal, Speer, Underwood, Sig Sauer, and others. It’s a niche cartridge with a loyal following, so it’s less common and pricier than mainstream rounds but still readily available online.

Is .357 SIG being discontinued?

No major manufacturer has discontinued it, though its market share has shrunk as agencies returned to 9mm. It continues in regular production for the shooters and departments that still use it. Expect higher prices and lower availability than 9mm or .40, but it is not a discontinued cartridge.

Can you buy .357 SIG ammo online?

Yes. In most U.S. states you can buy .357 SIG online and have it shipped to your door. You must be at least 21 for handgun ammunition, and some states and municipalities add restrictions or shipping limits, so confirm your state and local laws before ordering.