The Versatible 10mm

Am Shooting Journal ^ | 7/7/2021 | J Brooks

[w1n1]

First developed to combine the attributes of the 9mm Luger and the .45 ACP, this round is now one of the best handgun hunting cartridges made for semiautomatics.
Handgun shooters know that two of the most popular calibers are the 9mm Luger (Parabellum) and the .45 ACP. The latter is slow but makes a big hole, while the faster 9mm tends to lose energy quickly once it hits the target but shoots fast and flat. In a perfect world, a gunmaker would bridge these two rounds to make a fast and hard-hitting bullet.

It is this very idea that led Lieutenant Colonel John "Jeff" Cooper to come up with what we now know as the 10mm Auto. Back in 1983, the search began by looking at the speed of the 9mm Luger and the energy of the .45 ACP. The idea was that if a round could shoot fast, which means flatter trajectory, and could hit hard, then it would fit the military’s need, as well as that of law enforcement and civilian use for self-defense. The 10mm was created by taking a .30 Remington rifle case and cutting it down to .992 inch and opening the mouth large enough to seat the 10mm (.400-inch) bullet.

Overall length is 1.240 inches up to an acceptable 1.260 inches. The round shoots 180-grain bullets very well, but loads are available for lighter and faster projectiles down to 135 grains, which shoot nearly 400 feet per second faster than the 115-grain bullet out of a 9mm. It is also loaded with 200-grain powerhouses that shoot around 300 fps faster than the 230-grain .45 ACP. It seems that Lt. Col. Cooper was onto something when the 10mm was developed.

FIRST CALLED THE 10mm Super, the cartridge never really shined. This could be because there was already a 10mm Super on the market so a name change had to be made; this set back the rise to fame, as shooters didn’t know what the 10mm was all about. In 1989, the FBI decided to issue the 10mm to their agents. This occurred after the shootout in Miami, Florida, in which five FBI agents were injured and two were killed when they attempted to arrest two bank robbers. The agents were armed with .357 Magnums and .38 Specials, both revolvers.
After the incident the FBI realized they needed more firepower in their issued sidearms, both in ammo capacity and in bullet performance. Through testing, and like Lt. Col. Cooper, they decided the 10mm fit their needs. But there was one reason why the military and even the civilian world never really accepted the 10mm and that was felt recoil A fast and heavy round means there will be a bit of push back when you pull the trigger.

Smaller-framed agents couldn’t handle the recoil of the 10mm. When it comes to law enforcement, it is more important to hit your target with a light-shooting bullet than miss with a heavy one. For personal defense, a lot of times just producing a handgun will stop the encounter and then the loud bang could thwart the criminal. But for law enforcement, where each round has to be accounted for, it is imperative that the intended target is hit.
Because of this, the FBI decided to go with another new round on the market, very similar to the 10mm, the .40 Smith & Wesson (S&W). The .40 S&W was built on the 10mm case and bullet, using the same 10mm projectile but in a shorter case that held less powder, shot slower and therefore had less recoil. Most law enforcement departments today use the .40 S&W. Read the rest of versatile 10mm here.

[I cannot think of a name]

Try to find any ‘actual’ 10mm ammo. Most of what they pass as 10 is so downloaded that it's little better than .40.

Cooper intended the .10 to be equivalent to a .41 mag. If you can find any proper loadings, it is.

[Seaplaner]

I've heard much the same thing, that some Alaskan guides and hunters are switching to 10mm instead of 44 mag revolvers.

I would love to hear about bear attacks countered w the 10 mag

[dblshot]

Ain’t that the truth, probably with the 1/2 inch socket under the workbench.

[Secret Agent Man]

the only problem is if you have to use it, you lose it and won’t get it back

now it cant help you

carry inexpensive but working guns because you will lose them for years and they might come back in damaged condition, if they come back at all

[Paal Gulli]

Proof again why American Shooting Urinal is the most worthless, most inept gun website in existence.

Before the FBI adopted the .40 S&W, they were issuing a single-stack 10mm, the S&W Model 1076. Urban myth notwithstanding, the FBI never issued anything close to Col. Cooper’s idea of a “proper” 10mm load, only the 10mm “FBI Lite” load. Plus the all-steel 1076 empty weighs 10 ounces more than a Glock 20 so the fairy tails about FBI agents being intimidated by the 10mm’s ‘ferocious’ recoil are just that: fairy tales.

The proof of that is that the replacement .40-cal that the FBI selected fired the exact same bullet at the exact same muzzle velocity (= the exact same free recoil impulse) in the S&W Model 1006, a pistol that was only two ounces lighter than the 10mm Auto S&W 1076 but also was a full 15 ounces heaver that the full-size .40 S&W Glock 23.

Got that? The .40 S&W pistol that the FBI replaced their original 10mm with generated exactly the same free recoil as the 10mm FBI Lite load had, and the all-steel Model 1006 was a biscuit short of a pound heavier than the full-size .40 S&W Glock.

A POUND HEAVIER! And how many Soy Boys have you heard proclaiming the “petite” G23 too much of a handful to shoot?

[old curmudgeon]

The person who wrote this article is apparently not familiar with the subject.

For instance he does not even mention the .45 colt for which Cor-Bon sells a load that is 300 gr, 1,300 fps and delivers 1125.58 energy...according to the Taylor scale, not the scale used by most sources in which velocity is squared.

Now one can argue all night about which is the proper way to calculate killing power, but by the Taylor scale the Cor-Bon load has the killing power of the .45-70 which is the indisputable top bear killer.

Buffalo Bore has many more big calibers for those man enough to hang on to them.

This is a very interesting link. It discusses this very subject. https://buffalobore.net/Trail&CampGuns.pdf

My point is not to argue about what to carry but to point out that the person who wrote the article apparently is not very well informed.

[Gay State Conservative]

later

[Salamander]

*Every* time I see a socket set on clearance, only the 10mm is missing.

Somebody should sell a set of nothing but 10mm sockets.

They’d get rich.

[21twelve]

https://www.youtube.com/watch?v=v3rd_oikzgQ

Dude Dad’s 10mm socket holder!

[Salamander]

We ALL are.

:D

[Who is John Galt?]

I've heard much the same thing, that some Alaskan guides and hunters are switching to 10mm instead of 44 mag revolvers.
I would love to hear about bear attacks countered w the 10 mag

Using Handguns or Pistols in Defense Against Bears Update 104 cases 97% Success, 6 May 2021

[Who is John Galt?]

Try to find any ‘actual’ 10mm ammo. Most of what they pass as 10 is so downloaded that it's little better than .40.
Cooper intended the .10 to be equivalent to a .41 mag. If you can find any proper loadings, it is.

Looking at factory loaded ammo, the 10mm is a lot closer to .357 Magnum than it is to .41 Magnum. I think a lot of the guys who carry 10mm in bear country, do it simply because they like auto pistols...

[PapaBear3625]

16 rounds at a charging bear?

The odds of more than one bear being around is not necessarily zero, especially during mating season.

[TexasGator]

“The odds of more than one bear being around is not necessarily zero, especially during mating season.”

you will never get 16 shots off with charging bears.

[JD_UTDallas]

The Norwegians issue Glock 20s in 10mm specifically for polar bear defence and it has a proven track record with the Norwegian Artic forces in actual polar bear shootings. Good enough for the world’s apex land predator good enough for anything else that walks on land.

I own three 10mm two Glocks and a stainless EAA. I routinely go to Montana , Alaska and Idaho for geology reasons all of which have brownies and Alaska has polars . 220gr hard cast hand loaded to primer denting pressures yields crimp verified ~1400 fps in a compensated 6” barrel with a 28lb aftermarket spring. That’s 15+1 of real deal 44 mag energy , bullet weight and velocity. My model 29 Smith 6” shoots 240gr jsp at a crimp checked 1350 fps and 220 gr Barnes XTPs at 1450’

I’m not afraid to hand load to these levels in a fully supported lone wolf stainless barrel.

[JD_UTDallas]

Oh how I loath autospelling, crono verified velocity not crimp

[Myrddin]

16 rounds at a charging bear?

I know, it would be easier to just decline the card :-)

[Who is John Galt?]

I've heard much the same thing, that some Alaskan guides and hunters are switching to 10mm instead of 44 mag revolvers.
I would love to hear about bear attacks countered w the 10 mag

And one more (with a 10mm Kurz ;>):

MT: Defense Against Grizzly with Bow and .40 Caliber Pistol

[Who is John Galt?]

220gr hard cast hand loaded to primer denting pressures yields crimp verified ~1400 fps in a compensated 6” barrel with a 28lb aftermarket spring. That’s 15+1 of real deal 44 mag energy , bullet weight and velocity. My model 29 Smith 6” shoots 240gr jsp at a crimp checked 1350 fps and 220 gr Barnes XTPs at 1450’

That's "real deal 44 mag energy" only because you're comparing apples to oranges; your hot (maybe too hot) 10mm handload gets you into the ball park of some factory .44 mag ammunition. For one example of an apples-to-apples comparison, my most recent (2021) reloading manual lists 300 gr .44 Magnum loads at higher velocities than 200 gr 10mm Auto loads. That's 50% more bullet weight at higher velocities with the .44 mag, using data from the same source. Bottom line, the 10mm Auto won't ever be a .44 mag (or even a .41 mag)...

[TexasGator]

If you can rapid fire 17 rounds at that load you are the bear!