This is a guest post by Andrew Betts
10 mm auto is an extremely versatile cartridge that is quickly gaining in popularity. It offers the energy of .357 magnum in a rimless auto cartridge, which brings with it the benefits of faster reloads and higher capacity than you can get in a revolver. Some uninformed brutes of questionable lineage might claim that it is “too much” for defense, but those same buffoons are not likely to argue that the .40 S&W or .357 mag are “too much” (my apologies if you are a buffoon who understands that 10 mm isn’t voodoo magic).
See, 10 mm is capable of remarkable power for an auto pistol, but it doesn’t have to be loaded to the bleeding edge of SAAMI specs. Even at full
power, it doesn’t necessarily penetrate more than other pistol cartridges when it is loaded with the right bullet. If you carry a 10 mm for defense, you are clearly a wise person of noble lineage and you already know that. You may be interested in which loads for the 10 mm are best suited for defense, though, and that’s what we’re here to talk about.
So what makes a good defense load and which loads are best suited for defense in the 10 mm? Let’s start with what makes a “good” defense load for any gun in any caliber. The absolute most important factor is that it is reliable. It must fire every time and must not induce malfunctions in your firearm. Second, is needs to be accurate enough that you can make the right parts of the bad guy leak. It doesn’t need to be match accurate; a gunfight isn’t Olympic free pistol. It just needs to be accurate enough. No amount of terminal performance can make up for poor shot 
placement.
Accuracy and reliability are largely dependent on your specific firearm, though. Just because a load is accurate and dependable in my gun doesn’t mean that same load will work as well in your own firearm so you positively must test your chosen defense ammo in your gun. The third factor that is important in defensive ammunition is terminal performance. 10 mm has a lot to offer here, but it’s easy to get carried away. We don’t want a load that is so powerful that it recoils too much for you to get fast controlled pairs. We also don’t want a bullet that expands too much or comes apart and doesn’t penetrate adequately. Light for caliber bullets like this COR-BON 135 gr Pow’RBall produce dramatic looking wounds that seem impressive, but they don’t penetrate deeply enough to reliably incapacitate.
Good terminal performance for a defensive handgun round is defined by a bullet that penetrates a minimum of 12” but no more than 18” and expands as much as possible while still meeting that penetration standard. Pistol bullets, even the mighty 10 mm don’t move quickly enough for the temporary stretch cavity to contribute in any substantive way to wounding so the only two factors that matter in a pistol cartridge’s ability to wound are diameter and penetration. The bullet must also be capable of expanding despite passing through heavy clothing so testing is often conducted with the IWBA standard of four layers of denim. The velocity that 10 mm brings to the table helps quite a bit in this regard. Even generic target bullets such as this Montana Gold JHP still tend to expand and are not clogged by the denim as they might be at lower velocity.
That 165 gr Montana Gold is a great example of how 10 mm can make mediocre bullets perform well. Montana Gold JHP bullets aren’t designed or marketed as defense bullets. They are just a simple, old fashioned cup and core jacketed hollow point with scores around the opening of the hollow point. A bonded jacket like the Speer Gold Dot gives much better weight retention, though. Underwood’s 165 gr Gold Dot performed extremely well, although the recoil might be a bit much. On the other hand, in terms of raw power, expansion, tissue disruption, and retained weight, it’s hard to ask for much more. If you’re looking for the Tim Allen “more power” load, you found it.
Heavy recoil means a longer period of time between follow up shots, though. It doesn’t matter how macho you are, that’s simple physics. No matter how quickly you can shoot your .787 cal Super Kill-O-Blaster, you are able to shoot the same gun faster with lighter recoiling ammunition. Let’s go back to the idea mentioned at the beginning of the article that just because something can be done, that doesn’t mean it must. All that power that 10 mm has to offer is very useful for hunting or large animal defense, but it might be counterproductive if you’re trying to get quick hits on a bad guy who is trying to kill you.
If you are interested in something more moderate, the new Hornady 175 gr Critical Duty might be what you’re looking for. It isn’t full melt-your- face-off fuel injected 10 mm horsepower by any means. It’s a little hotter than .40 S&W can manage but still reasonable with quite controllable recoil. Its penetration and expansion are ideal for defensive use and the textbook perfect expanded bullet that looks like it fell out of an advertising brochure gives you warm fuzzies.
In my testing I’ve found that, with few exceptions, almost any 165 gr or heavier JHP bullet expands well and meets penetration requirements. Conversely, most 155 gr and lighter lead core hollow point bullets don’t make the minimum penetration standard. There are so many really good performers that it is difficult to point to a handful as the “best” but another that really stands out was Reed’s Golden Saber loads. Both the 180 gr and 165 gr versions performed well, but the 180 gr showed an incredible 1.058” for the maximum expansion measurement. Golden Saber is not a modern wonder bullet by any means but it is a proven performer with a great track record and this is no exception. As a non-bonded design, it is impressive to see it achieve perfect weight retention, especially at full power 10 mm velocity.
While limited penetration is the goal for personal defense in the city, a lot of folks carry a 10 mm for defense on the hiking trail, camping, or otherwise enjoying the wilderness and people who own a home in more remote areas sometimes have a higher risk of a dangerous animal on their property than human miscreants. In those cases, many folks prefer a load with more penetration than is typical for defense loads used in town. A heavy solid with a wide meplat can cut a wide, deep track through tissue and have the sectional density to crush thick bone. You might also want to have a bit of expansion just in case they are attacked by human thugs, though. If you want to have your cake and eat it too, with deep penetration and decent expansion, two loads really stand out. The first is Federal’s new 180 gr Trophy Bonded JSP. It penetrates to almost 17” and expands uniformly to about .60 caliber.
If you need even deeper penetration but still want to see some reliable expansion, PBR’s 200 gr XTP might be perfect. With 20” of penetration and nice, uniform expansion to just over half an inch, this may be the perfect woods load for any area that doesn’t have nuclear powered bears.As you know full well, 10 mm is the best millimeter and offers incredible potential. I couldn’t begin to write a truly comprehensive article covering each load that performs well in 10 mm pistols. Instead, I tried to highlight some of the loads that performed a little better than the rest. If I left out your favorite load, leave a comment and let us know. It’s also worth noting that 10 mm is being produced by more companies, in more flavors, than ever before, including some new offerings from some of the big names. If you would like to view the results of more 10 mm tests, visit my channel at: https://www.youtube.com/user/chopinbloc/ Or if you’d like see the results in spreadsheet format, visit the link below and click on the tab with the weight range you wish to view.
Andrew Betts served with the Arizona National Guard for over 12 years, including a tour to Afghanistan. Visit his YouTube Channel for more great shooting information.
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