10mm Caliber: Everything There Is To Know

10mm… another one of them-there fancy European “milly-meters?”… Nope – the 10mm is as American as apple pie, unlike its minus-1 cohort, the 9mm. That little gem came from Germany in 1901. Our 10mm is a bit newer - like, around 82 years newer. It was introduced in 1983… more history in a bit.

The 10mm is the be-all and end-all of the mainline production semi-auto cartridges. Sure, there have been more powerful rounds made to function in a handgun (for example, the three magnums… .357, .44, and .41). But, in terms of top power in a semi-auto pistol (or to continue in the hillbilly vein I started with) a “self-shucker”, the 10mm is about at the top of the heap. Velocity, energy, flatter trajectory… it has it all. It is truly the King of the Semi-Auto hill.

History

It all started in 1983. Col. Jeff Cooper, handgun expert, former Marine officer, and co-founder of the American Pistol Institute (later Gunsite Academy) in Paulden, Arizona was among the first proponents of what he called the “modern technique” of pistolcraft. His gun of choice was the 1911. His instructional techniques have proven to be effective and his legacy lives on.

He used the .45 ACP fairly exclusively, in terms of handgun calibers. However, he saw the need for a more powerful round that would be even better than the old .45 in terms of ending the fight. Theorizing that a bullet of .40 caliber weighing 200 grains at around 1000 f.p.s. would be the best bet for stopping a fight, he worked with Dornhaus & Dixon (D&D) and came up with a larger, more potent variant of the CZ75-platform pistol in a brand new caliber: 10mm. The gun was called the Bren Ten, which was a transliteration of Brno, the center of the Czechoslovakian gun industry and the caliber.

I’ve studied Jeff Cooper over the years and have read much of what he wrote. Knowing his fondness for the 1911, it is interesting that Jeff Cooper liked the CZ75. He was, pretty much, a died-in-the-wool 1911 acolyte and considered double-action pistols the “answer to a question that hadn’t been asked”. But, he saw the value of the Czech pistol (mostly because you could carry the CZ75 “cocked and locked” if desired. He pushed the development of the 10mm with a variant of that type of pistol as the base. 

Norma of Sweden made the ammo in the beginning, with Federal coming online later. Norma was all you could get at the start. D&D had troubles pretty much from the beginning. They rushed these really expensive (for the time) guns into production without proper QC and thereby sent guns to dealers that had problems. Shipping guns without magazines didn’t help – the mags had issues. So, the gun was made for only three years. D&D folded the Bren Ten tent in 1986.

Gone?

10mm might have been relegated to the trash heap of history were it not for Colt introducing their excellent Delta Elite 1911 in 1987. I’ve reviewed this pistol - a good friend owns one. It is a primo 1911. That introduction helped keep the cartridge around, and then the F.B.I. helped it along when they adopted it and the S&W 1076 pistol in 1990. This was great until some agents complained about the strong recoil that the 10mm generated. 

(I often wonder if the 10mm’s popularity might not have dipped as it did in the ‘90s if the F.B.I. had allowed its desk agents and other non-field-personnel to carry something lighter in recoil, like the 9mm). They even adopted the H&K MP5 in 10mm for special teams. Anyway, things went along until the agency asked S&W to load the 10mm down so its agents wouldn’t have to fight heavy recoil. S&W did them one better and shortened the case from 25 to 22 mm and loaded it lighter.

Enter The .40 S&W

This morphed into the .40 S&W, or as some shooters who put beer on their Wheaties call it, the “Forty Short & Weak”. We all know where the .40 went –  it’s still going. It is not quite as popular among LEOs as it once was, but plenty of them (and civilians) still like it and carry it. The 10mm, however, has regained a lot of its popularity among shooters – especially hunters and those who tromp the bear woods. I counted at least 16 companies that make 10mm pistols, and that does not count carbines. It is the most powerful rimless pistol cartridge out there, to the best of my knowledge.

Ballistics

Speaking of power, the 10mm has more energy at 100 yards than the .45 ACP does at the muzzle. Let’s all kick the poor ol’ .45 while it’s down, right? No way! I like the ancient round – I just wrote it up for this blog. I will continue to respect the old warhorse, but I know that the 10mm is way better for hunting or just about any other use (except maybe for concealed carry – more about that later). 

Here’s a peek at how it compares to a few other handgun cartridges…

.45 ACP – I just mentioned how the 10mm outclasses the .45. The SAAMI sets the .45’s top pressure limit at 21,000 psi, while the 10mm comes out of the muzzle every time at 37,500 psi max.

.40 S&W – The .40 operates at a pressure of 35,000 which puts it at a disadvantage of between 250 - 300 f.p.s. when compared to the 10mm. That’s the main reason why the .40 is more comfortable to shoot than the 10mm.

.357 Magnum – It says a lot for you to be able to compare a semi-auto cartridge with magnum revolver rounds. The very fact that the 10mm holds its own against the .357 speaks volumes. Operating at 35,000 psi, the .357 was the 800-pound gorilla of handgun cartridges in terms of power when it hit the streets in 1935. LEOs were starry-eyed over the fact that the cartridge was purported to stop gangsters' cars with hits through the doors or into the engine. The .38s they had couldn’t do that, even the .38-44. So, the .357 was the darling of LEOs and handgun hunters for many years.

The 10mm will equal many .357 loads and even surpass a few others. The real advantage of a 10mm over a .357 in many shooters’ eyes is the fact that you can carry anywhere from 10 – 15 or so rounds in your pistol as opposed to 6 or 8 .357s. Will it fully replace the .357? No way – the .357 shoots .38s, remember, which makes it versatile and the full-charge 125 grain load is one of the best stoppers out there. But it does pretty good for a self-loader’s cartridge.

.41 Magnum – This not-so-popular revolver round got its start in 1964. The previous year, revolver heavyweights (please remove your hats) Bill Jordan, Elmer Keith, and Skeeter Skelton (put your hats back on) petitioned, asked, bugged and otherwise harangued S&W to bring out a .41 caliber that would fall between the .357 and .44. Elmer’s idea was to bring out two loads… a full-tilt hunting load consisting of a 210-gr JHP at around 1350 f.p.s.

The other load was to be a 200-gr hard semi-wadcutter out the tube at 900 f.p.s. for police use. Remington chose to cater to its velocity-is-everything clientele and did not produce a police load, just the moose-stomper one. Couple the heavy recoil with big, heavy N-frame guns (41 oz), and … it’s been nice to know ya. (Most .38s in use at the time weighed around 30-34 ounces and had half the .41’s recoil). 

So where does the 10mm come in on the velocity chart compared to the .41? It hangs right in there. The .41 puts a 210-gr bullet out at about 1350 f.p.s. There are several loadings that will put a 200-grain bullet out of a 10mm’s muzzle at 1300 f.p.s. (Double Tap is one that comes to mind), for 750 ft.lbs. of whump. That’s pretty close and isn’t really much of a competition since the .41 never did really catch on like its smaller and larger brothers. I’ve seen exactly one S&W .41 Magnum in all the time I’ve been around guns, 50 years. It was a great idea but it just didn’t catch on. (If you are a .41 shooter, great – it’s a great caliber, for sure!) But, for the rest of us, I’d stick with the 10mm.

Let’s look at one representative velocity and trajectory chart. This is for the not-overly-energetic S&B 180-gr JHP, with a 25-yard zero. I picked such a load over the barn-burners to show that even on the lower side of the velocity scale the 10mm is still no slouch. Such a load as this might come in handy in either bear or close- range deer woods…

Putting things into perspective, even with this non-maximum load at 100 yards, there is a decent amount of energy left. If you were hunting deer, you would of course limit your range but you shouldn’t feel under-gunned. You really shouldn’t feel under gunned with any 10mm load. Plus, more and more manufacturers are coming out with handguns and AR platform carbines and pistols due to their gaining popularity in the hunting, self-defense and competition markets.

Applications

OK… you just rode down to your favorite gun shop and picked up a brand-new 10mm and some ammo. Now what? Well, hopefully, you’ve put a little more thought into that decision and have an idea of how you’ll want to use your new big boomer. What can you use a 10mm for? Here are a couple of ideas…

Hunting

This is the premier reason to own a 10mm, in my opinion. Of course, not every shooter has been a handgun hunter as long as I have. I tend to pursue four-legged-critters in the woods and fields with a gun that I can carry on my belt. Do I not like rifles? Perish the thought. I’ve killed deer with rifles ranging in caliber starting from .243 and up. It’s just that I favor the short gun. 

I would gladly take a 10mm into the woods around our house (or our son and daughter-in-law’s property which adjoins ours) gladly. Most shots that I’ve had have been at 150 yards or in, and that was in the field across the highway. A 180-gr JHP or JSP in a deer’s boiler room at 75-100 yards would put her (or him) down. Most of my handgun deer shots have put the bullet through the critter and have zipped off to parts unknown. I welcome the opportunity to hunt with a 10mm. The plus is that you can pick up a carbine in that caliber and have the ability to reach out a little further, given the bumped velocity and better sights (see below).

Competition

If you shoot USPSA or IDPA matches, you probably won’t see too many 10mm pistols. But there are some shooters out there who want to mix things up and be a bit different… sometimes they win, but all the time they are there to have fun. The 10mm duplicates, and then some, what the .40 S&W does in competition. Many shooters won’t want to put up with the extra recoil over the .40 or the 9mm but for those who don’t mind it, it could be rewarding.

Self-Defense

Here is the one area where I’m not going to recommend carrying a 10mm unless you are carrying “dumbed down” mid-range ammo. Don’t get me wrong. I know there are many of you out there who regularly carry a 10mm, and I applaud you. I’m directing these comments toward new carriers, folks who may not have a ton of experience shooting pistols. For experienced shooters who can manage the recoil, the 10mm is very effective. But, you still need to be aware of what’s behind your target – the 10mm can go through whatever it hits. 

I see the 10mm shining in the role of a home-defense carbine. Case in point… we live in the sticks and have two chicken coops with nothing behind them of value. I was typing at our kitchen table a week or so ago and looked up, just in time to see a coyote lope across the yard, snag a loose chicken, and make good his escape. Another incident happened just last night – a possum in a coop yard. Both of these varmint predators needed shot but I couldn’t get a gun into play quick enough. Here is the case for that 10mm carbine at the ready. These were more serious threats to our critter population than the two or three raccoons that have stolen our cat food over the past months, but they all need to be dealt with and the 10mm would do the trick.. 

In terms of defending your home, you may have the possibility of coming up against the two-legged variety of varmint. Again touching on where we live, we get lots of folks turning around in our circle drive. It doesn’t take a Paranoid Perry to know that some of them may not have our best welfare on their minds. So, a quick-into-action 10mm would go a long way to help create a feeling of calm in some situations.

Range/Fun

I can think of no more fun than an hour or two spent at the range shooting a 10mm. Not only would it be fun for you, but also fun for those around you. Even though the 10 is probably as popular as it’s ever been, it’s still rare enough that it tends to draw a crowd behind the firing line. With ammo becoming more available, I am seeing the more “exotic” calibers reappearing in greater numbers. The 10mm is one such chambering.

10mm vs. 9mm  

We all pretty much know about the 9mm. This little cartridge exhibits a good balance between power and controllability, effectiveness, cost, and easy handling. Let’s face it… you can take a teeny gun like my Springfield Armory Hellcat RDP and shove 15+1 rounds into it. That’s a lot of shooting! Stick an extra mag or two on your person and you’re set. But, what about the 10mm? 

You have to decide for yourself what you will carry, what you will defend your castle with, what you will take to the range… I see a reason to own both. But what if you can’t do that? What if you’re on a budget? That’s gonna constrain you a bit. 9mm pistols come in all price ranges, starting at under $200. The least-expensive 10mm that I’ve seen has been the EAA Witness 14-round CZ clone at $495. You can buy more than two Hi-Point C9s for that amount if that’s your idea of a good time. OK, that’s a snarky thing to say but you get the point… 10s are gonna cost more than 9s. And, in defense of the C9, it flat works and if it quits for any reason  they’ll fix it or send you a new one. Been there, done that, have the T-shirt…

How about ammo? There’s no doubt that 10mm ammo will cost more than that for a 9mm. It’s the nature of the beast. 9mm is used by militaries worldwide, not to mention by every police agency in every city that has a vowel in its name or so it seems. There is plenty of 9mm around, and it will cost less than 10mm ammo.

Shooting the two? There isn’t a terrible, horrible amount of difference in felt recoil (well, 12 ft./lbs for the 10 vs. 4 for the 9, at least) but it’s there. It does take some getting used to, especially shooting it off a bench. I tend to shoot better offhand where the recoil feels lighter. As with most anything, you can learn to shoot a 10mm well… it just takes practice. 

I would say that for typical, everyday-type shooting or concealed carry, the 9mm might be the way to go. But if you have any reason at all to need more, by all means, step up to the 10mm. It does just about everything the .45 ACP will do and then some.

What About A 10mm Carbine?

I talked a bit above about the carbine version. A few years ago I might not have made the following statement, but my experience with pistol-caliber carbines has grown a lot since then… you ought to consider getting a carbine in 10mm. Don’t neglect the pistols but don’t exclude the longer guns.

I’ve found that my 9mm carbine just beats my pistols all to heck in terms of accuracy, velocity, and hitting what I aim at. Now, I’m neither the best nor the worst pistol shot in the room but the advantage of placing that stock against your shoulder and lining up the optic with the target… that just beats open pistol sights all hollow.

Add about 400 more ft/seconds velocity for a 9- to 16-inch barrel and its attendant energy gain and you’re in business as you’ve never been before. Here, you could open up the range at which you hunt, whether hogs, deer, or whatever. I could see a hard-cast bear load 200-grain bullet moving out at around 1400 f.p.s. – now, you’re talking!

Doing a little speculating, I came up with a Shooterscalculator.com trajectory chart for the above load. I ran it to 300 yards, but in real life you wouldn’t (or shouldn’t) go past 150 or so and even that depends on the exact load and conditions. Here’s the chart:

We see that our little experiment in longer-barrel-ology creates a bullet drop of only a foot at 300 yards. That’s getting into rifle territory, but with a heavier bullet. Figuring the muzzle energy, we come up with a figure of 870 ft./lbs. That’s nothing to sneeze at! If you were to bushwhack a deer or hog at, say, 50 yards, the bullet would most likely truck right on through and depart for zip codes unknown. I’ve had that happen with my hard-cast .44 Magnum reloads at speeds not even close to 1400 f.p.s., so I know that a really hard 200-grainer would definitely punch right through. Talk about great bear protection… 

Anyway, my ramblings here are just to show you that, of all the common semi-auto handgun cartridges, the 10mm would most likely be the one to get the most out of a carbine’s barrel. Whether you are a cop trying to stop a bad guy or his car or a backyard farmer protecting your chickens (guilty as charged), the 10mm would do everything from punching through a car radiator or door to putting Mr. Coyote’s lights out and more.

Conclusion

Are you looking for magnum-style performance out of a self-loader? Want more than 6 rounds available? Prefer a pistol over a revolver? Check out the 10mm. I’ve shot this caliber on several occasions, many times, and I never get tired of it. Fifteen or so rounds in the magazine, flat gun that carries well in dangerous country, the power to take a large critter out with one or two shots, reliability out the wazoo… what’s not to like?

Add in the versatility of being able to buy both dragon-stomper and target loads (not to mention what handloading could do) and we have a winner, winner, chicken dinner. This goes double if you get your hands on a carbine with its longer barrel. Do you shoot 10mm? Let’s hear from you below!