10mm/40 caliber?

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You can shoot .40S&W out of a 10x25mm semi-auto pistol.
But, it is not safe to do so.



After the 1986 FBI Miami shootout (8 FBI agents vs 2 bad guys = 2 bad guys KIA, 2 FBI KIA, 5 FBI WIA of which 2 medically retired due to the injuries. 1 bad guy did all the damage to the FBI and had been shot 3 times with 9mm prior to doing so), the FBI determined that the 9x19mm was an inadequate service round and looked for a replacement. After testing, they determined the 10x25mm was what they wanted.

S&W and Winchester created the .40S&W, after realizing that the ballistics of the underloaded 10mm "light" rounds that the FBI were using could be replicated in a smaller package.

In the early-1990s, the FBI issued the 10x25mm S&W Model 1976, but due to compliants about the size/weight of the handgun from field agents, it was replaced by an interm pistol in the mid-1990s, the 9x19mm SIG P-226/P-228 (agents had a choice). In the early-2000s, the SIGs were replaced by the .40S&W Glock 22/23 (agents have a choice).
 
You can shoot a .40 in a 10 mm. Just switch out the barrels and your ready to go. Most guns do not require a magazine, extractor, or recoil spring change. Swap a 100mm barrel for a .40 cal barrel and away you go. :)
 
The answer is, yes you can shoot a .40 S&W in a Colt Delta Elite. To be precise, a Colt Delta Gold Cup. I had a handful of 10mm in my pocket and somehow managed to let a .40 S&W slip into a mag full I was loading. No big drama, no kaboom, no damage. The next round jammed the empty .40 up into the chamber beyond the reach of the extractor and it had to be poked out from the muzzle. The .40 obviously headspaced on the extractor and was in position for the FP to reach the primer. Not really sure what the sequence of events was that lead to the case slipping the extractor and being stuffed into the chamber.

Now, the disclaimer. This .40 was a reload 180 gr fmj. I'm not sure which batch it came from but all of my .40 loads are somewhat reduced loads. I had been shooting 10mm lites and the recoil/report was not that much different, so the .40 could have been one that was just mildly reduced. I expected to see something picture posting worthy from the .40 case but, no joy, looked like about every other one I've ever seen. I kind of expected to see a Glock smile all the way around it.

So, if you want to shoot reduced load .40's single shot and glomb up your chamber and risk a case failure, and poke out the hulls from the muzzle, knock yourself out. It's really not all that much fun to use a single shot Delta.

OH BTW, the way to do it is get yourself a Fire Dragon 6" ported .40 S&W barrel. Drop it in, and go to shooting .40's. Your 10mm mags will work for the most part and so will your stock recoil springs.
 
I read that article three or four times. My question, which I suppose is beside the point, is why does one ejector holding the rim of the cartridge not provide adequate headspacing? I understand it's not designed to work that way but it seemingly does, and it does indeed hold the cartridge against the breech face in the same position (at the breech face) the 10mm cartridge would be. The difference as I see it is not there unless somehow that ejector is not adequate (please explain if it is indeed not) but rather at the mouth of the shell. The 1/7" gap would be there and the bullet would have to find it's way into the barrel from the chamber. That's what worries me. I'm a novice so please explain any illusions I have here...
 
10/40

...It would seem HOLDEN, that you have pinpointed something. Under Ideal circumstances, all cases would headspace on the casemouth, realisticaly most dont.

Smith and Wesson basically adopted the Centimeter cartridge, Invented by Paul Liebenburg, to their 9mm platform guns. Hence the .40 cartridge. the difference being basically a small pistol primer to avoid detonation or firing by the ejector upon the removal of live round. When the .40 S&W was born, so was the Performance Center. Head Gunsmith/ Director?....The same Paul Liebenburg.
Paul Created the Centimeter for IPSC by cutting the original 10mm down for better feeding etc. The 10 was developed in conjunction with the Bren Tenand was heralded as an Ideal compromise between capacity and knock down power.

Chuck W
 
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There is no Finer Fighting Handgun...

...than the Glock 20.

Too many FBI agents shot limp-wristed and ruined a good thing...for the FBI.
 
Magnumdood I hate to tell you this but the Glock 20 wasn't what the FBI were using when they adopted the 10mm, it was the Bren Ten that was used. In fact teh Glock 20 wasn't invented until 1991. And there were/are plenty of problems with using a 10mm, especially with full loads. Many pistol frames couldn't handle the power of full loads and needed constant maintenance and that means more money, etc. etc. While I love the 10mm and in a 1911 it's my choice for carry the .40 S&W is cheaper, universally more controllable and will do the job the FBI, and any other shooter, need it to do for target and for defense against humans.
 
OK. here's the deal.
I've grown reluctant to take anything I see on the internet at face value so I decided to try to replicate Dean Speir's results.

I'm going to have to call my single previous experience with a .40 inadvertently being fired in my 10mm barrel an anomally. Possibly because of the fact it was a reload. As I said, it was waiting patiently in the chamber to be poked out and showed no ill effects. I don't know where it started out, under the extractor or up in the chamber.

I loaded up 6 WW white box 180 gr fmj into the 10mm mag and fired them up making sure to see that each was captured by the extractor. They all went bang, ejected properly and the cases showed no signs of any problem whatsoever.

I then loaded one round into the chamber, closed the slide and fired. This case ejected normally, though closer than the others. It was the spitting image of most of the cases in Speir's article. Primer flatter than a pancake and nicely perforated and a nice little nick on the head where it jumped over the extractor.

So I guess the moral of the story is if your gun won't capture the .40 underneath the extractor and lets it slip over and headspace on the casemouth you can expect flat, perforated primers and premature extractor wear. OTOH, if it captures the .40 behind the extractor against the breechface pretty much all you're looking at is premature wear and dirtying up on the casemouth ridge in the chamber. How long it would take to fatally damage the ridge I have no idea but these will be the last .40's to ever go through my 10mm barrel.
It's so much easier just to put in the correct barrel.
 
my 2cents

I reload .40 and 10mm. Except for the brass, they are the same. I put the same bullet in each one.
 
In an attempt to answer the extractor / headspace question.

The extractor in any 1911, or any other gun that feeds the round up under the extractor hook, simply cannot hold the case tight against the breech-face.

There has to be built-in hook clearance in order for a round to come out of the magazine at an angle and be able to slide up under the extractor hook.
Were it tight enough to hold the case back firmly against the breech-face, the round would bind up while feeding with the nose tipped upward and stop the gun.

If you hold a round in firm contact with the breech-face and look at the case rim / extractor hook, you will note quite a gap between the back of the hook and the front of the rim. This is as it would be when in battery and is controlled by the depth of the chamber and the case length.

Firing shorter cases, as a .40S&W in a 10mm chamber will allow the firing pin to drive the case forward against the extractor, fire it, and then chamber pressure drives the case rearward at very high speed against the breach-face.
This batters the gun excessively because the case gets a high-speed running start before hitting the slide.

rc
 
I understand what you are saying. What do you make of the advise commonly given for checking extractor tension of placing a round under the extractor and giving it a little shake? Supposedly it is to remain in place. Mine has never done that but I have just chalked it up to wear on the extractor. Mine has still never failed to eject or feed properly so I go with the "If it ain't broke, don't fix it." maxim. Perhaps the shaking deal is for going the other way and determining if the extractor is too tight? Mine looks like it might get a 1/32" or so of free run with a .40 held behind the extractor. I don't really see how that batters the gun, per se. The brass is the clear loser in the collision with perhaps the most solid point of the entire gun.
 
Yeah yeah yeah, and you can shoot .380 acp out of a 9x18Makarov pistol too. So said the gunstore coot when I came in looking for 9x18mak ammo.

Bottom line, beware of advice from old gunstore coots, and use the right ammo for the weapon.

But hey, it's YOUR hands and eyes, not mine.
 
Glock 20C - handgun perfection.

Demetrios,

I didn't see where I claimed the FBI used the Glock platform for their little foray into 10mm land. I'm well aware of what they used as well as when the 10mm was offered in the Glock. I really don't care if steel frames can't handle the pounding of the 10mm; the Glock frame can. I've shot well over 15K full power loads out of mine with nary a problem. The Glock polymer frames soak up a lot of recoil that causes metal frames a myriad of problems.
 
...The FBI never used the Bren Ten...neither did most Bren Ten owners.

The first FBI 10 was the 1006 if I recall correctly. Then the 1076
Click to expand...

it's pretty hard to use a Bren Ten without a supply of mags :D

the major downfall of the FBI selection of the 1076 as their platform of choice was their insistence on the frame mounted de-cocker...they should have chosen the Ruger P90

every 1006 (only 4) i've fired has been flawless...well, except for the weight :)
 
every 1006 (only 4) i've fired has been flawless...well, except for the weight
Click to expand...
I worked with a guy who carried the S&W 1076. Never had a problem. He was a pretty good shot too. The chickification of the FBI led to the creation of the S&W .40.
 
JFC, just buy a 40 s&w barrel for your 10mm and it will work fine. Iknow for a fact that a glock 20 will work just fine with the stanadard 10mm mags and recoil springs
 
I am hesitant to report this, but a good friend of mine has shot probably hundreds of .40SW rounds out of his Glock 20 with the factory 10mm barrel. Heck, I've done it. However, I do not recommend it. The right and safe way to do it is to get a .40SW conversion barrel.

-z
 
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