Underwood Xtreme Penetrator 10mm Ammo Test

By Glen Wunderlich

Decided to test some Underwood “Xtreme Penetrator ammo in 10mm Auto. Manufacturer claims 1500 fps and I can’t argue, because my Chrony must have been too cold to record the speed. The bullets are all copper and fluted

Fluted, all-copper 140-grain bullet

and engineered to penetrate and expand through hydrostatic pressure developed by the spinning flutes. The 140-grain bullet penetrated some 6 inches into wet-to-semi-frozen newsprint or magazines.

The Glock model 29 handled the rounds perfectly, as it does with everything. I have a rear sight laser, as part of this rig. It’s within the left portion of the rear sight and manufactured by Laser Lyte and no longer in production.

Glock 29 10mm Auto with rear-sight laser

I like it because it lines up well with the barrel – unlike some models in grips – and is completely adjustable. What I don’t like is if it goes haywire, I’ll have to come up with something else. Being a Gen 1 model, there’s no rail. I don’t necessarily “need” a laser but I like having one for extreme situations.

My typical carry ammo in 10mm has been 150-grain Corbon hollow points rated at some 1350 fps or so.

Either of these light-bullet loads are quite manageable, but for me, most things are.

I didn’t shoot for accuracy – just testing the ability to cycle and penetrate. Dang bullet looks like it could be reloaded but it expanded very well through the wet media. Didn’t save any for pictures except the pic of the hole through the antlers of that cover-deer. That hole was at the end of the line for the bullet.

Recoverd 140-grain Xtreme Penetrator from wet new media

Not sure the stuff is worth the exorbitant cost. Maybe a little more testing.