10mm, the cartridge, the myth, the legend

[Overkill338]

The 10mm Auto, it almost vanished into obscurity. The brainchild of Col. Jeff Cooper who set out to make a flatter shooting cartridge than his beloved .45 ACP. He wanted it to be able to push a 200 grain bullet to 1000 feet per second, and it was achieved by shorting a .30 Remington case, blowing out the walls so it would accept the bullet from the .38-40 Winchester, a .400" bullet. Basing a pistol off the CZ75 design, the Bren-Ten was born, but it came at a price. $500 was a lot of money in 1986 and the company ended up filing for bankruptcy. Luckily Colt decided to pick it up in 1987 and started producing a 1911 called the "Delta Elite". This pistol is part of the reason we still know about the 10mm today. The other reason is probably because agent Dove's 9mm bullet stopped one inch shy of Platt's heart in the Miami-FBI shootout (see 1986 FBI Miami Shootout). Some speculate that Dove and Grogan might have survived if that bullet had pushed one inch farther.

So the FBI decided they needed more powerful handguns. They adopted the 10mm Auto, in its full power form, it puts it square between a .357 Magnum and a .41 Magnum. They started using Smith & Wesson 1076 pistols. They were a variant of the S&W 1026, except the 1076 had a 4.25" barrel and a frame mounted decocker vs the slide mounted decocker on the 1026.They also contracted H&K to build MP5's in 10mm for their "SWAT" style teams, and those are still in use today.

After agents started using these new handguns, qualification scores dropped considerably compared to the old 9x19 pistols. The recoil of the full bore 10mm proved to be too much for most agents. They began testing with "Reduced Recoil" ammo to try to improve scores and make the guns more manageable. The request for the new ammunition was passed to Federal Cartridge. This is the loads that became known as "10mm Lite", and several makers still make loads in power range. Of course when they started using lighter loads, the pistols became reliability disabled. Smith & Wesson's solution was to take the case from 25mm to 22mm and they were still able to copy the performance of the FBI Lite loads. This new version of the cartridge became known as the .40 S&W, and it also fit in 9x19 size pistols, which let shooters with small hands handle them better, and qualification scores improved again. Law
enforcement agencies all around the US adopted this new cartridge and it has enjoyed great success.

The 10mm Auto has always been around in guns like the Glock 20, Glock 29, Colt Delta Elite and some more along the way. A lot of self defense handgun owners only ever considered the 10mm for a woods defense gun, when hiking or hunting. Everyone feared if used for self defense against human targets that over penetration would be a severe problem, hurting bystanders and going through walls. It wasn't until ballistic gel testing started to become popular that people learned the faster you pushed a hollow point bullet the LESS it penetrated. It actually takes well-constructed hollow points to handle the full power of the 10mm Auto. Bullets like the bonded Speer Gold Dot and the Hornady XTP. This turns the big 10 into a great self-defense firearm. Underwood Ammo, Buffalo Bore, & Double Tap Ammo are great places to get ammo tuned to get full potential out of the 10mm, 180 grain bullets at 1300 feet per second, and 200 grainers at 1250. They also sell 200-220 grain hardcast ammo for woods defense against 4 legged critters out to put you down. Plus here in 2016, the 10 seems to be making a comeback. You've got the Glock 20/29/40 and the Delta Elite like before, but now Sig Sauer is making a P220 in 10mm, Dan Wesson is in the game, Kimber, Nighthawk, STI, and Tangfolio too.




This isnt just about the 10mm's accomplishments as the cartridge itself. Let's not forget it's children that it has given us and their success as well. The .40 S&W, probably still the most commonly used law enforcement cartridge. The .357 SIG, pushing a 125 grain bullet at 1350 1450 fps (depending on ammo used), and quickly nipping at the .40 S&W's heels, as tons of LE departments are adopting it. The 9x25 Dillion, this one seems to be just for fun, because there aren't any .355" bullets that will hold up to its speed. 124 grain bullet at 1700
fps.





So when you are in a gun shop glancing around and see a 10mm pistol, don't just think of a cartridge that almost disappeared into firearm history. Think of how amazing the round is and maybe give it a chance, or at least be thankful for its offspring that citizens and LEO's carry every day. The 10mm Auto is here to stay, and there are those of us who like it, and love to feel that recoil of this amazing cartridge. For the hand loader it can be anything from a .40 S&W to something right up at the .41 Magnum. It's probably one of the most versatile cartridges in existence, just give it a chance.

[Overkill338]

P. S.: I'm an amateur writer, so look over it if I'm not perfect with typing please.

[4949shooter]

Good article, Overkill. I had seen it on Glocktalk and didn't realize it was yours.

Couple things I might add or change..

Colonel Cooper originally specified a 200 grain bullet at 1000 feet per second (something closer to .45 ACP +P ballistics). It was Norma who saw the potential of the 10mm case and loaded it to 1200 fps.

Also, the mainstream FBI agents never saw the full power load. The FBI marksmanship unit experimented with the heavy loads in a Colt Delta Elite, and determined it would be too much for the average FBI agent to handle. They asked for a reduced loading which is what went out to the agents.

I applaud your efforts. Please keep them up!

[Overkill338]

I have one written on the 460 Rowland, 357 sig, 45 GAP and the Glock 29 article never got to go live.

I fixed my doubled picture.

[Mike_Fontenot]

So the FBI decided they needed more powerful handguns. They adopted the 10mm Auto, in its full power form, it puts it square between a .357 Magnum and a .41 Magnum.
[...]
For the hand loader it can be anything from a .40 S&W to something right up at the .41 Magnum.

Underwood's loads (which always strive to be right at full-spec) for 10mm and .357mag have about the same energy.  10mm is a long way below .41mag.  Full-spec .41mag is not far behind full-spec .44mag.

[The_Shadow]

So the FBI decided they needed more powerful handguns. They adopted the 10mm Auto, in its full power form, it puts it square between a .357 Magnum and a .41 Magnum. They started using Smith & Wesson 1076 pistols. They were a variant of the S&W 1026, except the 1076 had a 4.25" barrel and a frame mounted decocker vs the slide mounted decocker on the 1026.They also contracted H&K to build MP5's in 10mm for their "SWAT" style teams, and those are still in use today.

Trying to keep the history correct;
Well the the variant was that of the 1006 with the slide mounted decocker/safety.  The 1026 is the 5" version of the 1076 with frame mounted sig style decocker.

[The_Shadow]

I'd like to also refer you all to an article I wrote for RangeHot.com
http://rangehot.com/original-10mm-ammo-made-ffv-norma-ab-%C2%B7s-670-40-amotfors-sweden/

Col. Cooper's numbers of 1000 feet per sec however Mike Dixon was able to finalize external specifications; he upped the velocity specification to 1150 feet per second.

NORMA actually sent the ammo which shoved the 200 grain TC 1260 fps from the 5" test barrel...

[sqlbullet]

Also, the mainstream FBI agents never saw the full power load. The FBI marksmanship unit experimented with the heavy loads in a Colt Delta Elite, and determined it would be too much for the average FBI agent to handle. They asked for a reduced loading which is what went out to the agents.

To add a reference to 4949Shooter's correct statement:

http://looserounds.com/2017/02/01/brief-history-fbi-semiauto-pistols/

The reduced power load was developed in December 1988, two years before the 1076 went general issue in December 1990.  Some academy agents did receive guns in July of 1990, but this was still eighteen  months after the 180/950 load was developed.

The issues with the 1076 were not reliability related, at least in terms of failures to cycle.  The FBI had mandated that the trigger pull be altered on the 1076 in order to accommodate FBI training of "trigger prep".  The changes to the trigger hooks created the possibility of the hooks locking up the drawbar rendering the gun out of service.  In this state the trigger could not be pulled, the hammer could not be cocked, and the slide could not be cycled.  The guns were recalled and did not re-enter general issue until October 1992, at which point there was little further interest in the 10mm.  The FTU had already moved on to the SIG 226/228 in 9mm Luger. 

It is interesting to note that the FTU also was very resistive to the 40 S&W.  It would be until 1997 for the FBI to begin issuing Glock 22/23 pistols in 40 S&W, and then the approved duty load was a mid-velocity 165 grain JHP, not the "FBI load" 180/950.

[4949shooter]

Well with you guys writing all these great 10mm articles I guess my writing career is over before it started. 

[dan10mmman]

So the FBI decided they needed more powerful handguns. They adopted the 10mm Auto, in its full power form, it puts it square between a .357 Magnum and a .41 Magnum. They started using Smith & Wesson 1076 pistols. They were a variant of the S&W 1026, except the 1076 had a 4.25" barrel and a frame mounted decocker vs the slide mounted decocker on the 1026.They also contracted H&K to build MP5's in 10mm for their "SWAT" style teams, and those are still in use today.

Trying to keep the history correct;
Well the the variant was that of the 1006 with the slide mounted decocker/safety.  The 1026 is the 5" version of the 1076 with frame mounted sig style decocker.

I need to go back and re read some stuff.....As I recall Col. Cooper wanted a 41mag with more rounds when he developed the 10mm.  A 200gr bullet @ 1250fps.  this was the original plan.  And please check your sources for energy.....for instance the Winchester Silver Tip....a reputable round.  The 10mm has a slight edge on the 41mag.  Both using 175gr sthp.  The 41mag is advertised @ 607lbs. muzzle energy.  The 10mm is advertised @ 649lbs.   

[sqlbullet]

Dan10mmMan, that Silvertip load is the 41 mag equivalent of the 10mm FBI load.

A number of gunwriters were of the opinion that the ideal law enforcement round was a 200 grain .410 caliber bullet loaded to 1250 fps.  They correctly understood that the 44 magnum was way too much recoil for police work.  The .410 was selected to preclude loading the new ammo in older .400 caliber guns that would not handle the pressure, like the 38-40. 

On the other end of the 41 magnum spectrum from the Silvertip round is the Buffalo Bore Heavy 265 loaded to 1350 fps and 1078 lb-ft, and a 210 grain JHP moving 1560 fps and 1135 lb-ft.

https://en.wikipedia.org/wiki/.41_Remington_Magnum

These loads illustrate they true "top end" of the 41 magnum, and the 10mm pales in comparison.

Here is an interesting article about the 41 mag:

https://americanhandgunner.com/the-14-magnum-turns-gold/

[DanielWatters]

Originally, Tom Dornaus & Michael Dixon went to Jeff Cooper with the basic concept of making a CZ-75 clone in .45 Auto, and solicited his imput on its ideal features. After making their initial "CSP80" prototype in .45 Auto, Cooper suggested chambering it for a longer version of the old .40 G&A wildcat.

While they couldn't find a way to contact Whit Collins, Dornaus & Dixon did have a copy of his Guns & Ammo articles on the .40 G&A. Dornaus and Dixon went to John Donnelly of Ballistek to make the first prototype ammunition from .30 Remington cases. Note that in early promotional materials, the early 10mm cartridges had slightly shorter cases than what we see today. With my uncalibrated eyeball judging against a neighboring .45 ACP case, the prototype 10mm case looks closer to 23mm than the final standard of 25mm.

Then it became a matter of finding a commercial ammunition manufacturer willing to complete its development. After US ammunition manufacturers refused to cooperate, Dornaus & Dixon finally succeeded overseas with Norma. When it came time to spec-out the 10mm cartridge for Norma, Cooper suggested a muzzle velocity of 1,100 fps, so that the projectile would be guaranteed to hit its target at a minimum of 1,000 fps out to ~100 meters. When the concept of the Bren Ten Compact came up, he then suggested that the cartridge be bumped up to 1,150 fps so that the short barreled Compact could achieve the magic 1,000 fps impact velocity. Michael Dixon then told Norma to spec the cartridge for 1,200 fps, apparently thinking that Norma's test fixture barrels would run faster than the normal production pistol barrels. Norma must have added their own cushion to that figure, as they ended up delivering an early lot of 200gr ammo that clocked at ~1,250 fps from the Bren Ten.

[dan10mmman]

Dan10mmMan, that Silvertip load is the 41 mag equivalent of the 10mm FBI load.

A number of gunwriters were of the opinion that the ideal law enforcement round was a 200 grain .410 caliber bullet loaded to 1250 fps.  They correctly understood that the 44 magnum was way too much recoil for police work.  The .410 was selected to preclude loading the new ammo in older .400 caliber guns that would not handle the pressure, like the 38-40. 

On the other end of the 41 magnum spectrum from the Silvertip round is the Buffalo Bore Heavy 265 loaded to 1350 fps and 1078 lb-ft, and a 210 grain JHP moving 1560 fps and 1135 lb-ft.

https://en.wikipedia.org/wiki/.41_Remington_Magnum

These loads illustrate they true "top end" of the 41 magnum, and the 10mm pales in comparison.

Here is an interesting article about the 41 mag:

https://americanhandgunner.com/the-14-magnum-turns-gold/


Thank you sqlbullet, I love the 41mag, still have my first one ....that I bought decades ago.  More have joined the club over the years.  In my post I was just trying to show that in certain well known and widely accepted rounds, the 10mm has more energy.  No 10mm could hope to touch my 41mag loads. But that is a whole different story.
as an afterthought....my 41mag's will never hold 16 rounds like the 10mm.
I really enjoyed the links......thanks again
dan10mmman........formally known as dan41magman.........

[dan10mmman]

[Olgo]

LOL, that's a joke chart. That's the atomic blast imposed in the picture.