OK. Why go with a 10mm pistol? Power. Lots of power. Large heavy bullets at high velocities. Add in the newest higher capacity pistols on the market, and now you are fielding 15 shot magazines chock full of magnum speed bullets.

The 10mm is certainly not the most popular choice for everyday carry but is currently known as a very solid hunting/backwoods caliber with some hearty people carrying it for self-defense. I like the round and have ever since I saw Sonny Crockett carrying one way back on Miami Vice in a Bren Ten.

My first 10mm pistol was obtained as a result of  my friend, 10mm fanatic Ted Nugent, telling me “I thought you’d be carrying a 10 by now! You need to get one.” Now I am a full grown adult, and know what peer pressure is, but when Ted Nugent says you need one, you probably do. Like everything else Ted does, he is emphatic about this cartridge.  I am willing to bet Ted’s consumption of 10mm and pistols may have kept that market afloat during the lean times. I buy boxes. Ted buys pallets. Hell he had his own Ted Nugent brand 10mm cartridges!  So I finally got a 10mm some years ago and emailed Ted how I obtained it and how I loved the cartridge and it’s diverse loadings etc.  Ted, normally not a man of few words, wrote back “Welcome to Man Land.”

The 10 mm story is a pretty fascinating bit of handgun lore. It was “invented” with the help of Col. Jeff Cooper back about 1983 when he and a couple of others like Irv Stone (Bar-Sto Barrels) were looking for a “fighting handgun cartridge” to exceed the Colt .45 ACP. They cut down .30 rifle brass into a long shell that was 10mm or .40 inches in diameter. They also collaborated with a gun maker to stuff it into a kind of overworked CZ-75/Hi-Power Hybrid new semi-automatic pistol called the Bren Ten.

Ballistically the 10mm was doing things unheard of in a semi-automatic pistol. It was pushing an average 180 grain bullet from 1150 fps to 1400 fps depending on the loading. Comparing it to the combat king .45 ACP at 950 fps in 180-230 grain bullets, they found the 10mm at 100 yards still exhibited more speed in feet per second than the .45 did at the muzzle. It also had much less drop over that distance.

.357 Magnum was pushing standard 158 grain bullets generally between 1150 and 1250 fps. So, the low end of the 10mm loadings was still as fast or faster as the much renowned .357 fight stopper, and the 10mm used a larger diameter and heavier bullet. Stuff a bunch of ‘em in a semi-auto pistol (many more than a 6 shot large revolver) and you really had something new on hand.

Some people equate the 10mm to the .41 Magnum, but looking at the loading data, the very fastest 10mm was still just touching the bottom level of .41 Magnum loadings. Think of it more as the “.40 Magnum!”

Featuring the Bren Ten pistol on Miami Vice helped push the cartridge with public demand, but the gun company had issues, and could not keep up with making magazines for the Bren Ten and it faded away. It nearly killed off the 10mm right there.

Then the FBI Miami Shootout occurred in 1986. If you aren’t familiar with it, two former Army Airborne soldiers were active bank robbers in the Miami area, and an FBI stakeout team forced a vehicle stop to apprehend them. It was a shootout of epic proportions. Both bank robbers were eventually killed as well as two FBI agents and five more were injured.145 shots were fired.

This shooting has about 100 different learning points within it. The Gunfight at the O.K. Corral is the most studied shoot out in America, and the Miami shooting would be the second most analyzed. If you are not familiar with it, you should go look it up. Lots to learn there, and the FBI had to reexamine many of their training and equipment protocols.
In a nutshell, the bad guys were all shot up- but did not die like you would expect. In fact, after shooting all the agents, the primary bad guy got back in the getaway car and prepared to drive off. They did not escape when a wounded agent crawled to the car and stuck a gun in the window and added some more bullets to the mix.

Autopsies showed both of the bad guys had received numerous wounds (one had 12 bullet wounds and the other 6), several of which would have been fatal-but they just did not die at the scene. So, the FBI looked at the big question “Why not?”

Gun people can debate fast vs slow bullets, heavy vs light bullets, energy transfer and velocity till the cows come home. At that point in history the FBI decided penetration was the issue.

The FBI had two Rem 870s in play, three S+W 9mms, several .38’s and two .357 magnums. Of particular note, one of the SWAT trained agents hit the primary bad guy with 9mm rounds which did not penetrate enough to incapacitate. So, the FBI went in search of a better bullet/penetration package and found the 10mm. Winchester and Smith & Wesson supported the project with Smith building the first 1006 pistols. The 10mm cartridge penetrated rather famously and met the FBI’s idea of what a bullet should be doing downrange. (I have never encountered a block of ballistic gel in the street, but the 10mm killed a lot of them during testing.)

The FBI found one problem though, you had to put the 10mm in a large frame pistol like a .45 to handle the energy generated and to fit the longer shell casing. So, the guns were bigger. This did not play too well with people with smaller hands or less hand strength. Next, the full house 10mm loads were pretty potent-no escaping physics. Recoil was more than the issue 9mm and could be a problem. So, they downloaded the powder to slower velocities for issue ammunition under a 180-grain bullet in a load called the FBI Lite.

The guns broke a lot, and had to be reworked back at the point of manufacture. The FBI issued 9mm’s back to the field in the interim, and then came up with another new idea. They sawed off a bit of the brass and put the same bullet in it and now it was the new .40 S&W. It kept the larger diameter of 10mm but at slower speeds (about the same as a .45 ACP) and now you could put that shorter cartridge in a 9mm sized frame instead of a larger full size .45 style frame.

Like it or not, the FBI sets the standard for American Law Enforcement, and almost every agency dropped the 10mm and the 9mm to go to the new .40 S& W. Later in life, the FBI dropped the .40 and went back to the 9mm…and so did law enforcement.

I have never seen the 10mm compared like this before, so let’s pretend I just “discovered” it- the 10mm is to the .40 S&W the same as the .357 Magnum is to the .38 Special. The more powerful cartridges are just sitting in longer casings. They shoot the same weight bullets and are the same diameter as their big brothers. Everyone knows you can shoot .38’s in a .357 Magnum. Well in a pinch you can shoot the .40 out of a 10mm. Now there are cautions galore via manufacturers and internet commandos about doing it, or doing a steady diet of it, but yes you can shoot a .40 out of a 10mm- in a pinch or emergency setting. You may also be able to seat 10mm rounds in 45 ACP mags too.

I have never seen a lethality study on just the 10mm in the hands of law enforcement. All the other popular calibers are well documented by Greg Ellifritz and the FBI-just no 10mms. With the ballistics paralleling or exceeding those of the .357 Magnum, I would assume the 10 would perform similarly. The best practical assessment I ever got was from a former Virginia State Trooper who talked about liking the 10mm round and “Everybody we ever shot with it-died.”

The old 10mm joke was it was good for shooting burglars…who were hiding behind a refrigerator….in your neighbor’s house…across the street.

So, after the FBI left the 10mm like a piece of parsley on a truck stop plate, it almost disappeared again. But some big bore shooters kept it alive along with a company from Austria you may have heard of called Glock. They saw the cartridge as a winner and built Glock 20’s- full sized frame guns shooting that magnum level round. The frame was essentially the same as their full sized .45 the Glock 21, but the barrel and slide had to be changed to handle the longer and more powerful 10mm.

S&W showed up with a 10mm revolver too. It was interesting. H+K briefly had some MP-5’s chambered in 10mm and for quite some time it was pretty much an all-Glock show if you wanted a 10mm pistol. Then EAA Witness put out a high capacity 10mm and gunsmiths started building up 10mms in 1911 frames. I have “some” 10mm’s, and to me a Rock Island Armory in a Commander Length frame is cooler than a teenager cruising in a convertible on a Saturday night.

Glock brought out the first compact 10mm, the Glock 29, a twin to the .45 Glock 30 and the 10mm finally became much more compact to carry daily and with 10 rounds of high-potency pills outdoorsmen started toting them along too.

The internet is awash in 10mm as a bear protection gun articles and comparisons and sightings of them being carried by fishermen and guides in Alaska as last-ditch defense guns. I have carried 10mms in Wyoming grizzly bear country and felt good about the high capacity and magnum ballistics.

However, even the .44 Magnum doesn’t come near rifle ballistics, and no one in Alaska hunts giant brown bears with a .44 Magnum. Pistols are most likely noisemakers, and heaven forbid they have to be used in self-defense. You need really good marksmanship and good penetrating bullets in an exciting and hectic few seconds. Up north they take a rifle or a shotgun with slugs for serious protection. I have offered internet level advice to trolls talking about shooting bears with a pistol: “Save the last round for yourself. It will let you avoid a lot of crunching and screaming sounds.”

10mm’s keep on coming. Current high grade and high-capacity models are offered via FN, Springfield Armory and S&W. Last year Sig Sauer brought their 10mm to the market stuffed inside their now famous P320 modular platform.

The Sig XTEN is a full-sized gun in their similar sized P320 .45 frame with their excellent X grip module and X-Ray sights. I wanted it immediately, but it was still big, including a 5-inch barrel- roughly the same size as a full size 1911. It holds 15 rounds of 10mm.

I like the striker fired P320 platform and carried a 9mm P320 on duty for my last two years of federal service (leaving my venerable P226 at home) and shoot a full sized 9mm P320 in 3-gun competition. I also watch Sig making model changes and treatments of the P320, and now the P365 every couple of weeks! Seems the design teams just keep coming up with new ideas just for the Halibut. “Hey let’s do a P320 Legion!” “OK. Schedule that one after the Escalade, Accord and Silverado models.” Glock could take a lesson there, when was the last time Glock showed a new original product vs “Oh, same old Glock now with sprinkles!”

So being the calculating tight wad I figured if the 10mm XTEN was a hit, the people at Sig might see they needed to make it smaller. Sure enough, one year after introducing the XTEN they now have the shorter XTEN COMP on the market.

XTEN COMP is a 3.8-inch barrel version which still holds 15 rounds of high kinetic energy. It is still on the P320 frame in a nearly 9mm sized polymer frame and has the tunable Fire Control Unit and excellent X-grip. It is of course tapped and cut out for adding an optic if you wish (PRO DPP cutout.) The big feature which sets this pistol aside from all other 10mms is the presence of a huge single chamber compensator which reduces gas pressure, recoil and muzzle flip and makes it easier to make follow up shots.

The compensator is said to reduce the flip by up to 30%. My hands are not calibrated to measure that. What I did feel was a much softer recoil even with some pretty stout loads. It is undoubtedly the softest shooting 10mm on the market right now. It takes a lot of the sharpness out of recoil, and you get more of a very manageable push similar to a lightweight or officers sized .45 frame.

Recoil is a given, and everybody views it differently. It is certainly nothing to be afraid of, but sometimes it is a problem and the comp on the front end of this pistol is a welcome built-in accessory. It is much more shootable than the compact Glock 29 which has the same length barrel as the Sig but weighs 8 ounces less unloaded.

Is the Sig Sauer XTEN COMP the perfect 10mm? No, it is not perfect. But it is pretty darn good, fairly compact, comfortable to shoot, in a 15-rd. package, and Sig Sauer level dependable.

A couple of things I don’t like: Sig of course has a rather high opinion of their products and this one retails for $950 for a polymer frame gun. Steep, but it is a high powered 10mm and fanatics like myself will forgo groceries dollars if the gun is right. Sig will also control the MSRP, and you won’t see deep discounts for at least a year. The original Sig XTEN is a year old, and it sells for a bit less than the new COMP model but still has high dollar signs.

The other thing I don’t like, is if you weren’t aware, Sig uses their own aiming system called the “Optimal Sig Sauer Sight Picture.” “Normal” sight picture might put the target on top of the front sight/rear sight outline or a 6 o’clock hold. Sig doesn’t do that. Next up, a combat sight picture or Sight Image 2, puts the dead center bullseye on top of the front sight/rear sight profile. Sig doesn’t do that either. They use “Sight Image 3” whereby, using three dot sights, they have you line up the three embedded dots on the front/rear sight with the center of the bullseye…and they are calculated to strike dead center with this hold at 25 yards.

Failure to use the dots method will have your bullets striking low on the target. I don’t know about you, but I have done an awful lot of speed shooting and am pretty certain I have never seen the dots go by. I just shove the gun into the middle and press the trigger, and with my aging eyes am just happy to see the sight outlines at all!

You can train more with the gun to get your sight picture right or buy a smaller front sight. Or in a rather unique offer, you can send your gun to Sig, and they will have two engineers shoot it. If they concur it is unreasonably low, they will replace the front of rear sights and send it back to you. If they shoot it in the prescribed Sig Sight Image 3 manner and find the gun shoots like they want it to they will send your gun back with a bill for $110.

On a thousand dollar pistol I would like sights which hit point of traditional aim like all the other manufacturers in the rest of the non-Sig Sauer world. Ah well no pistol is perfect, and it gives me something to fuss with and a decision whether I will mount an optic on it.

If you have any 10mm stories send ‘em. I’d like to read them.

7 thoughts on “A 10mm Tale.”
  1. God damn it Keleher. Just ehat I need is a new caliber and another damn gun. And a holster, mag pouches, spare mags & all the fixins. You effin salesman you. You are an asshole. (Said with love.)

    1. David just call it a “house gun” and got get one…you always need another house gun to go along with the others who after all can get lonely…

      This new Sig has only been on the market since January. Exactly 2 holster makers in the U.S. are selling perfect fit for that model. The 10mm is just enough larger it won’t fit in any of my other 20 or so P320 holsters I have lying around (note in case of fire my house will be really hot from all the melting Kydex)….ordered up a custom built holster sitting in the parking lot outside the gun store! It’s no longer “gun money” it is for “accessories.” Regards.

  2. Mike, we must have been taught in/by the same generation: Never fire your gun dry – always save the last one for yourself. Enjoy the 10mm.

    1. Oh I do enjoy them…Adventure Wife doesn’t quit understand how a not perfect gun could bring me joy and stuff to work on. On the way to pick it up she said I should shoot it first to make sure it is the one I want. Had to explain (sweet as you please) “This isn’t Wal-Mart. You don’t get to try ’em on in the store or return them with a liberal return policy!” Thanks for reading.

    2. Agreed, in the firearms world “liberal return policy” means the firearms gets seized from the home. O.K. – this now begs the question. Does this holster make my butt look big???

  3. I sent this over to Ted this morning. He called me and said it only needed one correction: He is the actual Czar of 10mms!

    The FBI leaving the 10mm behind like a piece of parsley on a truck stop plate cracked him up too.

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