Last reviewed: 2026-04-18 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
The Underwood 40 S&W 140gr Lehigh Xtreme Penetrator is a lead-free self-defense round engineered for maximum barrier penetration and deep wound channels. CNC-machined from solid copper, the fluted Xtreme Penetrator nose design creates hydraulic pressure spikes that produce permanent wound cavities over twice the depth of most hollow-point projectiles — all while maintaining a straight penetration path through intermediate barriers. At 1200 fps and 448 ft-lbs of muzzle energy, this round delivers controlled energy transfer without deformation or deflection. Nickel-plated brass casings resist corrosion, feed reliably in all action types, and simplify reloading. Flash-suppressed powder, boxer-primed, non-corrosive. 20 rounds per box.
Built for the Box
Underwood loads the Lehigh Defense Xtreme Penetrator projectile — a monolithic copper design that cuts through glass, wallboard, sheet metal, and heavy clothing without yaw or tumble. The fluted nose channels fluid outward on impact, generating radial pressure that expands the permanent wound cavity while the blunt meplat crushes tissue. Sectional density of 0.125 supports deep straight-line penetration. Nickel-plated brass cases resist tarnish in leather holsters and humid environments, and the flash-suppressed powder preserves night vision in low-light defensive encounters.
Specs at a Glance
| Spec | Value |
|---|---|
| Caliber | 40 S&W |
| Bullet weight | 140 grains |
| Bullet type | Fluted solid copper (Lehigh Xtreme Penetrator) |
| Muzzle velocity | 1200 fps |
| Muzzle energy | 448 ft-lbs |
| Rounds per box | 20 |
| Case | Nickel-plated brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Lead-free | Yes |
| Intended use | Self-defense |
| Manufacturer | Underwood Ammo |
Underwood field-tests every lot with real-world firearms to verify consistency across platforms. This round fits shooters who prioritize barrier penetration and straight-line wound channels over expansion-dependent performance. Pair with modern striker-fired or hammer-fired pistols chambered in 40 S&W. See the full 40 cal ammo catalog for additional defensive and range loads.
Safe Handling & Compliance
Federal law requires purchasers to be at least 21 years old 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.
- Four rules: Treat every firearm as loaded, never point at anything you’re not willing to destroy, keep your finger off the trigger until sights are on target, know your target and what’s beyond it. NRA firearms safety rules.
- State and local laws: Verify that this ammunition is legal in your jurisdiction. Some states restrict lead-free projectiles, fluted designs, or defensive loads. Consult local ordinances before purchase.
- Solid copper rounds: Clean the barrel more frequently than with jacketed lead-core projectiles. Copper fouling accumulates faster with monolithic bullets; use a copper-removing solvent and brush after every range session to maintain accuracy.
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