Last reviewed: 2026-04-18 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
Underwood’s 357 Sig Xtreme Defender ammo pairs a 65-grain Lehigh Xtreme Defense fluted solid with nickel-plated brass and flash-suppressed powder, delivering 2100 fps muzzle velocity and 636 ft-lbs energy. The fluted copper projectile creates radial fluid displacement on impact, generating a permanent wound cavity twice the diameter of conventional expanding hollowpoints while maintaining 16-18 inches of penetration through barriers including wallboard, sheet metal, and automotive glass. For shooters carrying 357 Sig pistols in roles where barrier penetration and consistent terminal performance matter — law enforcement, executive protection, or prepared citizens in vehicle-heavy environments — this load offers engineered terminal mechanics without reliance on expansion.
Performance at a Glance
The Lehigh Xtreme Defense projectile is CNC-machined from solid copper, eliminating lead entirely and maintaining structural integrity after contact with hard barriers. Radial flutes channel hydraulic pressure inward, building cavitation while sharp edges cut tissue. The 65-grain weight at 2100 fps produces minimal recoil compared to heavier 357 Sig loads, allowing faster follow-up shots. Nickel-plated cases resist corrosion during carry and feed reliably in all action types. Boxer primers and reloadable brass extend the utility of spent cases. Underwood Ammo manufactures this round in the United States, subjecting each lot to real-world testing in duty-grade pistols.
Specs at a Glance
| Spec | Value |
|---|---|
| Cartridge | 357 Sig |
| Bullet weight | 65 Grains |
| Bullet type | Fluted (Lehigh Xtreme Defense) |
| Muzzle velocity | 2100 Feet Per Second |
| Muzzle energy | 636 Foot Pounds |
| Rounds/box | 20 Round |
| Case | Nickel Plated Brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Intended use | Self Defense |
| Manufacturer | Underwood Ammo |
This 357 Sig load fits any pistol chambered in the cartridge — SIG P229, Glock 31/32/33, Springfield XD(M), and similar duty-sized or compact platforms. For more defensive handgun ammunition across calibers, browse our 357 Sig ammo collection.
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.
- Treat every firearm as if loaded; muzzle in safe direction at all times.
- Verify current federal, state, and local laws governing ammunition purchase and possession in your jurisdiction before ordering.
- This ammunition contains lead compounds. Wash hands thoroughly after handling. Per California Prop 65, exposure may cause cancer and reproductive harm.
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