Underwood 500 Auto Max 420gr Xtreme Penetrator Ammunition, 20-Round Box

Underwood 500 Auto Max ammunition (model UW928) chambers one of the most powerful semi-auto handgun cartridges available with a 420-grain Xtreme Penetrator bullet. Unlike a hollow point, the Xtreme Penetrator is a solid, non-expanding design that uses a fluted nose to cut a wide, straight-line wound channel instead of mushrooming on impact. That flute geometry is engineered to maximize penetration depth rather than energy transfer near the surface, a deliberate design choice for shooters who prioritize deep penetration through barriers or heavy muscle and bone. At 420 grains, this is a heavy, hard-hitting bullet weight suited to the 500 Auto Max’s serious power ceiling. Each box holds 20 rounds of this specialty load.

Key Specifications

• Chambered in 500 Auto Max, one of the most powerful semi-auto handgun cartridges on the market
• Loaded with a 420-grain Xtreme Penetrator bullet
• The Xtreme Penetrator is a solid, non-expanding design, unlike a traditional hollow point
• Uses a fluted nose to cut a wide, straight-line wound channel and maximize penetration depth
• Packaged 20 rounds per box

Frequently Asked Questions

Does the Xtreme Penetrator expand on impact? No, it’s a solid, non-expanding design; the fluted nose is engineered to maximize straight-line penetration depth rather than mushroom like a hollow point.

What is this load built for? Its deep-penetration design suits shooters who need to defeat barriers or heavy muscle and bone rather than maximize near-surface energy transfer.

Buy the Underwood 500 Auto Max 420gr Xtreme Penetrator Ammunition

Order this Underwood Xtreme Penetrator load through our Underwood lineup of handgun ammunition. Order from our Lubbock, Texas gun shop and it ships fast to your door.