10mm Self Defense: A Suitable Defensive Cartridge?

For years—decades—9x19mm Parabellum has reigned as the go-to self-defense cartridge. Nothing can last forever, though, so maybe it’s time a new cartridge became the frontrunner. It isn’t as though none have tried. 380 ACP seems to make random surges in popularity but remains relegated to the realm of micros and backup guns; new rounds like 30 Super Carry are too unproven to own the market.

What cartridge is already proven as a stellar performer with a lot of guns chambered in it? 10mm Auto, of course. So why can’t the new hotness (which admittedly isn’t very new) be 10mm self-defense?

10mm Self Defense ammo in use
The big cartridge seems to be gaining traction lately, but does 10mm ammo really work as a self-defense round? (Photo credit: Kat Ainsworth Stevens)

Who Invented 10mm?

There’s some back and forth regarding who really, truly invented 10mm. However, it’s well known the idea first came from the late Colonel Jeff Cooper.

Back in 1976, Cooper founded what’s now called Gunsite Academy—it was known as American Pistol Institute when it was new—and is respected in many circles for creating the Modern Technique of the Pistol. Cooper hung out with such pistol greats as Jack Weaver, Elden Carl, Thell Reed, and Ray Chapman. He’d spent years shooting, training, and analyzing, and decided the gun world would benefit from a bigger bore defensive round. Something that could push a 200-grain bullet at high velocities; a cartridge to outpace the 45 ACP while maintaining its bulk. Oh, and he didn’t want the new cartridge to have a significant or rapid drop on longer shots.

Colonel Jeff Cooper, assisted creating the 10mm
The late Colonel Jeff Cooper founded what is now known as Gunsite Academy and also played a pivotal role in the creation of the 10mm. (Photo credit: Gunsite Academy)

In 1982, Cooper and a few other dedicated shooters, like former Guns and Ammo editor Whit Collins and pistolsmith Irving Stone, decided to get going with a collaboration to create the new cartridge. It started out like a lot of cartridges do: By modifying an existing cartridge. It was the 30 Remington they decided to cut down and load with a 40-caliber bullet. With the general idea in hand, Cooper went looking for a manufacturer to fine-tune it.

Dornaus and Dixon Enterprises INC.
Dornaus and Dixon was brought into the 10mm timeline by the late Col. Jeff Cooper. (Photo credit: Bren Ten.com)

According to the 1984 Dornaus & Dixon catalog, the creation of 10mm Auto went something like this:

Dornaus & Dixon Enterprises was formed in December 1979 with the combined efforts of two men, Thomas F. Dornaus and Michael W. Dixon, who had decided to build what they hoped would be the heir to the Colt .45 Auto. In January 1980, they went seeking advice from the most knowledgeable sources available. This effort naturally led to Jeff Cooper. Upon seeking his advice, it was discovered that Jeff Cooper, likewise, was working on such an arm. It was decided that Dornaus & Dixon and Jeff Cooper would join forces, with Jeff Cooper providing conceptual design criteria, as well as technical advice based on his vast practical experience, and Dornaus & Dixon providing the engineering, development, manufacturing, and marketing expertise. To retain his professional objectiveness, Jeff Cooper is not an employee of Dornaus & Dixon Enterprises, nor does he have any authority in the manufacturing of the Bren Ten.

On July 15, 1981, Dornaus & Dixon Enterprises, Inc. became a legal entity and was incorporated by the Secretary of State, in the State of California. On November 1, 1982, the manufacturing facility was dedicated in Huntington Beach, California.

Basically, Cooper went to Dornaus & Dixon Enterprises for help, and then Norma was brought in. At the time, Norma was known as FFV Norma AB (today they’re Norma Precision AB). Norma’s involvement in creating the 10mm Auto happened because Dornaus & Dixon Enterprises approached them for help. If you’re looking for a precise sequence of 10mm events, good luck. Everyone wants to claim so-and-so did this or that, leaving the 10mm’s history a little messy.

Federal Premium Ammo for 10mm self defense ammo
Federal Premium Ammunition has a number of fantastic 10mm loads available. (Photo credit: Federal Premium Ammunition)

10mm Self Defense

The 10mm cartridge is a more than respectable self-defense round if the shooter is able to manage it. 

It doesn’t matter if you love or hate the legacy of Cooper and Gunsite, what matters is how well this cartridge performs. 10mm is a cartridge capable of fantastic performance, even when it isn’t loaded as hot, as most manufacturers tend to tone it down with today’s factory loads. It outpaces both 9mm and 45 ACP even when those two are loaded as overpressure rounds. Take, for example, Hornady’s Critical Duty line:

Hornady Critical Duty 9mm +P 135 grain 45 ACP +P 220 grain 10mm Auto 175 grain
Muzzle Velocity 1110 feet per second 975 feet per second 1160 feet per second
Muzzle Energy 369 foot-pounds 464 foot-pounds 523 foot-pounds
Hornady Critical Duty 10mm 175 grain for 10mm self defense weapons
Hornady’s Critical Duty 10mm 175 grain is a good option for self-defense use. (Photo credit: Hornady)

There’s no debate regarding how fast 10mm leaves the barrel of a gun compared to other handgun cartridges, but can it maintain its velocity and energy? Check out the rest of the Hornady Critical Duty comparison below:

Hornady Critical Duty 9mm +P 135 grain 45 ACP +P 220 grain 10mm Auto 175 grain
Velocity at 50 yards 1039 feet per second 927 feet per second 1061 feet per second
Velocity at 100 yards 984 feet per second 887 feet per second 990 feet per second
Energy at 50 yards 324 foot-pounds 420 foot-pounds 437 feet per second
Energy at 100 yards 290 foot-pounds 384 foot-pounds 381 foot-pounds

Keeping in mind that 10mm is the only cartridge here not loaded as an overpressure, or +P, round, we can see it continues to perform well. It would appear it’s worth some consideration.

Is 10mm Good for Self Defense?

10mm self defense weapon holstered
Choosing a self-defense gun is a personal decision based on a variety of factors. Can 10mm work for you? Yes, it probably could. (Photo credit: St-Louis Dispatch)

It is, but as with any cartridge, there are considerations to be aware of. The top issue mentioned when 10mm is being discussed for self-defense use is the risk of over-penetration. Because it’s a more ballistically powerful cartridge than the other common defensive loads, it does penetrate more deeply. This is what makes it such a stellar option for handgun hunting, but it could also mean it over-penetrates a two-legged predator and strikes an innocent person. Does that mean it’s a lousy idea for self-defense? Absolutely not.

10mm is a workable defensive round. It’s more than capable of stopping a threat, there are a lot of models of guns chambered in it, and it can be quite precise. Regardless of what caliber handgun you carry for self-defense purposes, you are responsible for every shot fired. That means being capable of following the four safety rules, even when you’re fighting for your life. The rules being, of course:

Gunsite Firearms safety rules
The Gunsite Academy safety rules. (Photo credit: Gunsite Academy)

The 10mm was literally designed to be a superior defensive round. There are many gun owners who do carry their 10mms for self-defense use, but it isn’t exactly a mainstream practice. Whether or not it should be depends on far too many factors such as hand size and skill level. That’s because when it comes right down to it, you need to select the correct gun and caliber for your needs and abilities, not whatever is cool or popular. If that’s a 10mm, more power to you (literally). If it’s a 9mm, yes, that’s also a good defensive round.

It would be nice to see 10mm make a comeback—or would that be a first-time running as a favorite?—but it seems to be in the distant future. There are more 10mm loads being produced as well as a larger number of guns chambered in it being made. The time of the 10mm is coming. You’ll see.

Kat Ainsworth Stevens is a long-time outdoor writer, official OGC (Original Gun Cognoscenti), and author of Handgun Hunting: a Comprehensive Guide to Choosing and Using the Right Firearms for Big and Small Game. Der Teufel Katze has written for a number of industry publications (print and online) and edited some of the others, so chances are you've seen or read her work before, somewhere. A woman of eclectic background and habits, Kat has been carrying concealed for over two decades, used to be a farrier, and worked for a long time in emergency veterinary medicine. She prefers big bores, enjoys K9 Search & Rescue, and has a Master's Degree in Pitiless Snarkastic Delivery.


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