Last reviewed: 2026-04-19 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
For shooters running 300 Blackout subsonic ammo suppressed or through short-barreled platforms, Underwood’s 194-grain Lehigh Maximum Expansion load brings controlled expansion that activates on fluid tissue — not drywall, bone, or sheet metal. At 1025 feet per second, this lead-free solid copper hollow point sits well below the sound barrier, cycling reliably in AR-15 pistols, SBRs, and bolt guns while maintaining 453 foot-pounds of energy at the muzzle. Nickel-plated brass cases feed smoothly, resist corrosion during storage, and reload without tarnish. Flash-suppressed powder keeps your sight picture clean in low-light scenarios.
Load Profile
Underwood loads this cartridge to commercial SAAMI pressures, verified through barrel testing in real firearms — not just laboratory pressure guns. The Lehigh Maximum Expansion projectile uses hydraulic force to drive petal expansion on contact with tissue, opening to maximum diameter and holding that wound channel throughout penetration. Contrast this with traditional jacketed hollow points that mushroom and collapse along the shank, reducing effective cutting surface. The solid copper construction eliminates lead exposure at the bench and downrange, meeting range restrictions and state-specific lead-free mandates. Boxer-primed, non-corrosive nickel cases simplify brass recovery and reload prep.
The Numbers
| Spec | Value |
|---|---|
| Caliber | 300 AAC Blackout (7.62x35mm) |
| Bullet weight | 194 grains |
| Bullet type | Solid Hollow Point — Lehigh Maximum Expansion |
| Muzzle velocity | 1025 fps |
| Muzzle energy | 453 ft-lbs |
| Velocity rating | Subsonic |
| Lead free | Yes |
| Case | Nickel-plated brass |
| Primer | Boxer |
| Corrosive | No |
| Reloadable | Yes |
| Rounds per box | 20 |
| Intended use | Self-defense |
| Manufacturer | Underwood |
This subsonic load cycles suppressed AR-15s and bolt-action platforms without the supersonic crack, making it a practical choice for sound-sensitive applications. Browse the full 300 Blackout ammo inventory for hunting, training, and barrier-blind options.
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.
- Keep muzzle pointed in a safe direction; finger off trigger until ready to fire; know your target and what lies beyond
- Verify current state and local ammunition laws — some jurisdictions restrict lead-free or subsonic defensive loads
- Subsonic rounds may not cycle all semi-automatic firearms reliably; function-test your platform with this load before relying on it
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