Last reviewed: 2026-04-18 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
Underwood Xtreme Defender 45 ACP +P ammunition loads a 135-grain Lehigh Xtreme Defense solid copper fluted projectile at 1,335 fps and 534 ft-lb — velocity and energy numbers that exceed most full-weight 45 ACP loads while using a lighter bullet. This is a defensive load built around a permanent wound cavity created by radial flutes machined into a monolithic copper body, eliminating the expansion variables of traditional hollow points. For shooters seeking FBI-guideline penetration depth with lead-free construction and barrier-defeating geometry, the Xtreme Defender brings a fluted solid to the oldest service cartridge still in widespread carry.
Built for the Box
The Lehigh Xtreme Defense projectile uses six radial flutes machined into a solid copper body to create hydraulic pressure as the bullet moves through tissue. The flutes force fluid inward, building pressure that radiates outward into surrounding material — creating a permanent wound cavity that Underwood claims is over 100% larger than conventional expanding hollow points, without relying on expansion at all. Because the copper body never deforms, the bullet defeats intermediate barriers (wallboard, sheet metal, auto glass) without losing its wound-channel geometry or penetration depth. The result is consistent terminal performance across barrier and non-barrier scenarios, with penetration up to 18 inches in 10% ballistic gelatin. Nickel-plated brass cases are reloadable. Flash-suppressed powder reduces muzzle signature in low light. Lead-free construction eliminates California Proposition 65 concerns and meets range restrictions at indoor facilities. This is a +P load — verify your firearm is rated for +P ammunition before use.
The Numbers
| Spec | Value |
|---|---|
| Caliber | 45 ACP +P |
| Bullet weight | 135 gr |
| Bullet type | Lehigh Xtreme Defense (fluted solid copper) |
| Muzzle velocity | 1,335 fps |
| Muzzle energy | 534 ft-lb |
| Rounds per box | 20 |
| Lead-free | Yes (solid copper) |
| Case | Nickel-plated brass, reloadable |
| Flash suppressed | Yes |
| Intended use | Self-defense |
| Country of origin | United States |
| Manufacturer | Underwood Ammo / Lehigh Defense |
Browse the full 45 ACP ammo category for ball, hollow-point, and specialty loads.
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.
- Review the 4 rules of firearms safety before live fire.
- Verify firearm is rated for +P pressure. Consult your owner’s manual or manufacturer if unsure.
- Check your state and local laws before ordering ammunition online.
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