Underwood Ammo

Last updated and checked October 31, 2026 · By Nick Hall. Prices are the lowest new listings in our feed of 200+ retailers on October 31, 2026.

Buy a 10mm because you want the cartridge’s real punch, and it won’t be long before someone tells you to try Underwood Ammo. This Illinois loader is best known for its solid-copper Xtreme Defender and Xtreme Penetrator rounds, its Black Cherry hard cast bear loads and a very deep 10mm catalog. It costs more than range ammo, and it isn’t always the cheapest of the hot-load specialists. Here is who they are, what they make, and what is worth buying.

Table of Contents

Who Underwood Ammo is

Underwood Ammo is a Sparta, Illinois ammunition company that Kevin Underwood started in 2013. It loads handgun and rifle ammo for defense and hunting, and it’s best known for full-power 10mm, solid-copper Xtreme loads and hard cast.

The company’s own account of its start is short: Kevin Underwood saw a need for better ammunition at a reasonable price. Its site still says “100% USA Loaded” and “proudly loaded in Sparta, IL,” with components sourced in the US.

The big recent news is a second home. In October 2025, Georgia’s governor announced that Underwood would spend $41 million on a manufacturing and assembly plant in Effingham County, at Savannah Portside International Park, with 120 jobs. Construction was expected to begin in 2026 and hiring in 2027. That’s a lot of money for a company that was 12 years old at the time.

Here’s my favorite detail. Underwood has a Blemished section on its own store, and it tells you what’s wrong: discolored cases, missing polymer tips, unplated brass, or an average speed a little under the published figure. Some lots have a bigger disclosed difference, including primer-related concerns, and those sales are final. So read the note on each lot, and keep that ammo for the range.

On price, Underwood sits above the big makers’ practice ammo and around the other specialists. A box of 20 is the normal unit, so the 10mm loads on this page run about $1.15 to $2.20 a round.

What Underwood Ammo makes

Xtreme Defender

This is the company’s flagship carry round. It’s a lead-free, solid-copper bullet with flutes in the nose that push fluid sideways, so it doesn’t need to expand the way a hollow point does. MidwayUSA lists the bullet as Lehigh Xtreme Defense, and Lehigh Defense said in 2015 that Underwood’s line used its XD bullets. Underwood says most Defender loads are developed around the FBI’s 12 to 18 inch gel benchmark. On October 31 the 9mm 90 gr started at $25.20 and the 10mm 115 gr at $32.94.

Xtreme Penetrator

Same solid-copper idea, different job. The Penetrator is built to go deeper, so it suits people who care more about reaching something vital through muscle and bone than about staying inside 12 to 18 inches. Underwood itself says no bullet design can guarantee a particular depth, because speed, barrel length and test medium all change the result. The 10mm 140 gr ran $43.99 at Midway. There’s also an Xtreme Hunter that sits between Defender and Penetrator.

Black Cherry hard cast

For bears and big game, this is the line Underwood’s own team points to first. These are heavy, flat-nose bullets cast to 21 Brinell, then given the Black Cherry coating that helps cut lead fouling. Underwood says hard cast will go deeper than the Penetrator. You’ll see it in .38 Special, 10mm, .44 Magnum, .45 Colt, .460 Rowland and 454 Casull. A 10mm 200 or 220 gr box began at $26.35, and a 454 Casull 360 gr was $59.99 at Sportsman’s Warehouse.

10mm Auto, and the XTP and JHP loads

Underwood’s 10mm range is the reason many people find the brand. We had 34 Underwood 10mm listings in stock on October 31, from a 135 gr JHP to 220 gr hard cast. Conventional defense and hunting loads use bullets like the Hornady XTP. A 155 gr JHP was $22.99 at PSA, and the 180 gr XTP started at $24.47.

Rifle ammo and reloading components

The rifle side is bigger than the old reputation suggests: .300 Blackout, 6.5 Creedmoor, .450 Bushmaster, .458 SOCOM and .45 Raptor, plus a solid-copper Controlled Chaos line. The store also sells brass and other reloading components.

Build quality and the full-power idea

Underwood’s whole pitch is that many makers load down to cut recoil, wear or cost, and it doesn’t. Its FAQ says its 10mm isn’t +P, and that it’s loaded within SAAMI specs to get the cartridge’s original full-power performance. So a hot-feeling 10mm box isn’t automatically an overpressure box.

Other calibers need a closer look. Plenty of listings wear +P or +P+, and our Underwood review found 14 handgun listings carrying a label the SAAMI pistol and revolver standard doesn’t define. Underwood recommends standard-pressure ammo for routine practice, and warns against +P in an aftermarket barrel until you’ve confirmed it’s rated. Hard cast in polygonal rifling, compensators, ports or suppressors is a question for the maker of that part.

Nickel-plated brass runs through most of the catalog. Don’t expect every load to match its reputation, either. In our gel testing, the .380 +P XTP stopped short of 12 inches from a Ruger LCP, while the 9mm +P 147 gr XTP went 20.

How Underwood compares

The usual comparison is DoubleTap and Buffalo Bore, and price is where it gets interesting. DoubleTap’s 10mm 200 gr hard cast started at $20.01 and its 230 gr was $23.99 at Midway, while Underwood’s began at $26.35. So Underwood isn’t the bargain there. Buffalo Bore’s cheapest 10mm in our feed was $38.99, well above both.

What Underwood has that those two don’t push as hard is range in fluted copper, across Defender, Penetrator and Hunter. If you’re sold on that bullet, the other direct comparison is Lehigh Defense itself, and we cover its factory loads in a separate review.

Against Federal HST and Speer Gold Dot, you’re choosing between a fluted solid and a proven hollow point. Those majors are easier to find in stores. I’d pick one of those in a 9mm carry gun unless I had a reason to want the flutes, such as a small barrel that struggles to expand a hollow point.

Who should buy what

• 10mm owner, woods carry: 200 or 220 gr hard cast.
• 10mm owner, town carry: 180 gr XTP or 115 gr Xtreme Defender.
• 9mm carrier who wants solid copper: the 90 gr Xtreme Defender, which met its box speed in our Glock 17.
• Bear-country hiker with a revolver: heavy hard cast in .44 Magnum or 454 Casull.
• Lever gun owner: Underwood says its solid monolithic loads are safe in tube magazines.
• Bargain range shooter: the Blemished section, after you read the lot note.

Skip Underwood for high-volume practice, since brass-cased FMJ from a bulk brand costs far less. And if your gun is old, light or has an aftermarket barrel, sort out its pressure rating before you buy anything marked +P.

The Underwood philosophy

Underwood would rather sell you the top of what a cartridge can do than the middle. That’s a clear position, and it means the brand asks more from the buyer: know your gun, know the label, test your load. I respect that more than a box that promises everything to everybody.

How to choose your Underwood load

Defender or Penetrator is the question buyers ask most, and most pages that answer it never say what the choice really is. It comes down to how deep you want the bullet to go, and how much you’re worried about what’s behind the target.

Start with what you’re trying to stop. For people, start with an Xtreme Defender or a good JHP in your carry caliber. For bear, go hard cast first, since Underwood itself rates it deeper than the Penetrator.

Next check the pressure label against your gun’s manual and barrel. Then buy two boxes, not a case, and run them through your own pistol. Short barrels can lose speed, and the load has to feed in your gun. Compare stores, too. That 10mm hard cast ran from $26.35 to more than $33 on the same day.

A $41 million bet on hot ammo

Small ammo brands don’t often get a governor’s press release. Underwood started out serving people who felt big makers were holding back, and that niche has grown far enough to justify a plant in Georgia. Whether a bigger Underwood keeps the same feel is the question I’d watch once hiring starts in 2027.

Facts and Figures

• Founded: 2013, by Kevin Underwood, in Sparta, Illinois.
• Georgia plant: $41 million and 120 jobs in Effingham County, announced October 1, 2025.
• Hard cast: 21 Brinell, with Black Cherry coating and no separate gas check.
• Defender target: most loads developed around 12 to 18 inches of gel.
• Prices on October 31: 10mm 180 gr XTP from $24.47, 10mm hard cast from $26.35, 10mm Xtreme Defender from $32.94.

Shop Underwood Ammo & Prices

Live Underwood products and current prices, organized by caliber and updated automatically.

Where Underwood Fits in Our Buying Guides

• Underwood Ammo Review
• Best 10mm Ammo
• Best 9mm Ammo
• Best .357 Magnum Ammo
• Best .45 ACP Ammo
• Best Defensive Ammo
• Best Bear Defense Handguns
• Best 10mm Pistols

Underwood Ammo FAQ

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