10 Minutes of 10mm History

Posted by Rob Leatham

Find me on:

Aug 27, 2018 1:30:00 PM

10MM 10 Minutes

The 10mm auto is a curious cartridge. 

Designed originally as a best-of-all-options for the defensive pistol world, it was targeted to be an all things to all people service pistol cartridge. Sort of a hybrid of the service pistol standards, .45 ACP and 9x19 rounds. The goal? To have more capacity than the .45 and be more powerful than the 9mm. 

Without completely retelling the detailed history, in the early 1970s, the late Jeff Cooper was reportedly looking for a round that combined the advantages of both velocity and momentum. The ballistics of a 200 grain .400 (10mm) diameter bullet traveling 1000 feet per second looked good to Jeff on paper.


There was a problem, however. There wasn't a readily available cartridge case for an auto pistol that would handle that bullet diameter. So it wouldn't be as simple as just powering up an existing cartridge as had been done with .38 special, .38 auto and .44 special.

A new case had to be devised. 

Well, maybe not new, but altered and repurposed.

Similar “wildcat” cartridges had been developed previously using .224 Weatherby and .30 Remington brass. These had been chambered in a number of different guns. Most promising was the .40 G&A round developed by Whit Collins, followed shortly thereafter by the Centimeter and then the .40 S&W.

Of those, only the .40 S&W would ever make it into production, albeit much later, but the ground was laid for the 10mm as we know it.


When the design of this new hybrid cartridge occurred, a new gun (with design input from Colonel Cooper) was being developed to accept it. Known as the Bren Ten, it was basically a sized-up CZ 75.

Both the 10mm gun and round were in development about the same time. However, the ammo was finished long enough before the gun that people were becoming impatient to try this new hybrid. 

we had an interesting new round and nothing to shoot it in.

So, what to do? The combat pistol world was in its hey day and the buzz over this new combination was eagerly awaited by pistol enthusiasts worldwide. As time dragged on and the Bren Ten didn't seem to be happening, Colt stepped in and introduced a model to accept the 10mm. While familiar, it really wasn't the totally new, complete package we were all hoping for.


Remember that the design goal was originally to achieve a 200 grain bullet at 1000 FPS. This would deliver a flatter trajectory, greater penetration with a slightly higher level of power in both energy and momentum than standard .45 Auto (with the bonus of increased magazine capacity). 

Norma, the company that originally developed the 10mm, in their enthusiasm to make the round as good as modern propellents would allow, made their ammo far more powerful than was originally requested. The ammo was approximately 20% higher in velocity than the original specifications called for. While this sounds like a good idea, it was in fact not. At least not for service pistol use.

With that increase in power came costs that were just not worth it for the majority of shooters.

While exceeding the power of any other standardized auto pistol combination encountered, the gun/ammo combination was just too difficult for most to control. 

To add to the overall problem, the Bren Ten Pistol was long delayed and in the end, sadly never made it. Some were built, but they too couldn’t take the beating of the “hot” Norma ammo. Other manufacturer's 10mm guns did not deliver on the promise the 10 had made. They were harder to shoot than .45 in the same platform and did not hold up well to the very high-pressure ammunition. 

So for most shooters, the existing 1911 platform pistol with the powerful 10mm ammo just didn’t offer enough benefits to replace the already-available and time-tested .45 Auto. 


With no viable new gun, the high expense of ammo, and the excessive recoil that made it hard to control and shoot, the 10mm never became as popular as was hoped. And it mostly vanished from the public eye. 

But it didn’t die.

Although too hot for most applications for a service pistol, the 10mm with its potentially higher power levels continued [slowly] to make friends in the civilian and LE world. A lot of shooters still wanted a 1911 with more velocity, penetration, momentum, energy and flatter trajectory than the .45 offered. The 10mm’s devout but small following, by those who recognized its niche, soldiered on.


The FBI adopted the 10mm after the infamous 1986 Miami shootout, where they unfortunately discovered that they needed more gun, power and firepower than they currently had. 

The bureau soon concluded after the adoption, that existing 10mm ammo was “too hot” and as a result, requested a special lower-pressure load developed for them. This new load didn’t exhibit the same problems the original hot 10mm cartridges did, and proved a good compromise between power and controllability. 

This ammo was more inline with the original request. Due to the FBI adoption, the 10 was back in the limelight and major loading companies jumped on the band wagon.

Since then, the 10mm has continued to exist for both gun manufacturers and ammunition companies, albeit not as a best seller.  I sense a change in the air though...

Springfield Armory®’s 1911 TRP™ 10mms

Springfield now produces their top-of-the-line TRP™ in 10mm in both a 5” and long-slide 6” model. My favorite features are:

  • Forged Steel, Integral Accessory Rail
  • 5" Stainless Steel, Fully Supported, Match Grade Barrel
  • Ambidextrous Thumb Safety 
  • 3-dot Tritium Night Sights
  • SA Tactical Rack Rear Sight

But wait, what about all the 10mm problems of gun wear and tear and hot ammo?  

Better materials, 10mm-particular specifications and improved manufacturing capabilities allow us to produce superior, more-durable 10mm pistols. Specifically, one that will withstand the force of the “hot stuff” and still work with the lower pressure “standard ammo”. 

Flat out, the Springfield 10mm pistols are better than any previously available models from any manufacturer.

The only thing that could make our 10mm TRPs better, is if they were easier to aim. #OldEyes

Meet Springfield'S 1911 TRP™ 10MM RMR®

With the Trijicon ACOG® RMR® optic sight, this 1911 offers the ballistic advantages of the 10mm round in a strong, accurate, durable package with the latest in optical sights.

Here are 3 reasons that these TRP™ 10mm 1911s are more awesome than any of their predecessors (I like to think the Colonel himself would approve): 

  • First and most importantly, the GUN. Following our stringent TRP™ specifications, the Springfield 1911 with RMR® is a perfect fit for the cartridge. It’s the best of everything; quality, accuracy, durability, and reliability - a great handling pistol indeed. 

    You can drool over the TRP™ specs at Springfield-Armory.com, but I suggest you drop into your dealer to see and handle one for yourself. In your hands, there’s no denying the excellence and perfection. You‘ll feel the heft, the tight fitting of the slide to frame and the clean, crisp trigger pull. All the workmanship and upgrades that scream quality are readily tangible and visible.

  • Second - the optical SIGHT. For many shooters, aiming is difficult. Some eyes just don’t see that well. While vision issues can be resolved with glasses or contacts, there is almost always a compromise. You can correct vision to either the sights or the target, but one of them is NOT going to be in focus. 

    Optical sights allow focusing on the target. You never have to refocus back to the gun to align the sights. Seeing all the elements of a good sight picture clearly is no longer difficult. Look at your target and the dot is superimposed, showing the potential impact point of the round. The old argument of whether to look at the sights or the target no longer applies. Everything is in focus. 

  • Third - the 10mm CARTRIDGE. As we’ve discussed, the 10mm is the most powerful round commonly available that fits the 1911 platform. It can be a viable "all things to all people" chambering.

    For you speed junkies, the 10mm offers high velocity. Some loadings of the 10 have bullets going upwards of 1300 FPS. This guarantees high energies and flat trajectories.

    For the big-and-heavy-is-better guys, the 10mm bullet is .400 inch in diameter and regularly available in 200 grain weights. So it’s  a perfect fit for those who like the old saying, “I don’t care what caliber it is as long as it starts with 4”.

    Faster, heavier and bigger, the 10 is more powerful than the .45 and the 9. 10 is more than 9. There has to be some sort of "Spinal Tap" reference that is appropriate here… 

SA_TRP10MMRMR_StandoutGraphic 2


So thanks to all you stalwart 10mm fans, a purposeful caliber has survived and will continue to thrive into the future.

And if what you want in your next firearm is a pistol that is powerful, has range, is easy to aim, fun to shoot, high performing, with flat shooting ammo, then one of these Springfield Armory® TRP™s may just be your perfect gun. Check it out at the friendly neighborhood gun store and tell them Rob sent you.


Find a Retailer

Topics: Range Life

Springfield Armory® recommends you seek qualified and competent training from a certified instructor prior to handling any firearm and be sure to read your owner’s manual.  These articles are considered to be suggestions and not recommendations from Springfield Armory®.

Subscribe to Email Updates

Recent Posts