Last reviewed: 2026-04-18 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
For shooters running 357 Sig ammo in training cycles or range drills, Winchester’s USA White Box line offers a straightforward value proposition: factory-loaded cartridges assembled with components engineered for volume use, without the premium price of duty-grade defensive loads. This 125 grain full metal jacket round exits the muzzle at 1350 feet per second, delivering 506 foot-pounds of energy — performance that mirrors the ballistic profile of many carry loads, but in a non-expanding bullet design optimized for paper and steel targets. Winchester defines 357 Sig as a bottlenecked pistol cartridge developed for law enforcement use, combining the bullet diameter of 9mm with a necked-down 10mm Auto case to achieve higher velocity and flatter trajectory than traditional 9mm Luger.
Built for the Box
The USA line uses full metal jacket bullets — copper-jacketed lead cores that retain their shape on impact and feed reliably through semi-automatic pistols. Winchester loads these cartridges with clean-burning powder formulated to minimize fouling in high-round-count sessions. Brass cases are drawn from domestically sourced alloys, dimensioned to SAAMI specifications, and accept boxer primers — the same reloadable configuration found in premium defensive loads. Each round is assembled in the United States, with quality control processes that include case inspection, powder charge verification, and crimp uniformity checks before packaging.
The Numbers
| Spec | Value |
|---|---|
| Caliber | 357 Sig |
| Bullet weight | 125 grains |
| Bullet type | Full Metal Jacket |
| Muzzle velocity | 1350 fps |
| Muzzle energy | 506 ft-lbs |
| Rounds/box | 50 |
| Case | Brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Intended use | Range & Target |
| Manufacturer | Winchester |
The 125 grain projectile weight is the most common loading for 357 Sig ammo, matching the bullet weight used in many factory defensive loads and simplifying POI consistency across different ammunition types. Brass cases accept standard large pistol primers and remain dimensionally stable through multiple reloading cycles when processed with carbide sizing dies.
Safe Handling & Compliance
Federal law requires purchasers to be at least 18 years old for rifle and shotgun ammunition, and at least 21 for handgun ammunition. Ammunition cannot be shipped to certain states, counties, and cities — review our ammunition shipping restrictions before ordering. Store ammunition in a cool, dry location away from heat sources and out of reach of unauthorized users.
- Observe the four universal rules of firearm safety at all times — treat every firearm as loaded, never point the muzzle at anything you are not willing to destroy, keep your finger off the trigger until ready to fire, and be certain of your target and what lies beyond it.
- Verify that your state and local jurisdiction permits possession of 357 Sig ammunition before ordering — some municipalities restrict handgun calibers regardless of federal classification.
- This ammunition contains lead, a substance known to the State of California to cause cancer and birth defects or other reproductive harm under Proposition 65 — wash hands thoroughly after handling and ensure adequate ventilation when shooting indoors.
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