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Range Report 40 S&W in 10mm Auto??

ChadTRG42

Gunny Sergeant
Full Member
Minuteman
Jan 22, 2007
3,338
9
58
Dallas, Texas
www.dallasreloads.com
Is this possible? I've never done it (and won't try it), but talked to a guy who says he does with no issues out of a G20. They fire the same bullet, but the head spacing is .142 shorter on the 40 S&W than the 10mm. I would think this would keep the firing pin from striking the primer and/or cause pressure issues when it did strike the primer. Anyone tried this?
 
Re: 40 S&W in 10mm Auto??

I think you are correct. It's the fact that the cartrige can slide into the camber farther than it should. If the case was made like the 38sp/357mag then it wouldn't matter as much. I would think you could get away with firing 40s&w in a 10mm revoler cuase the moon clips would hold the case from entering farther into the cylider.

Someone correct me if am wrong.
 
Re: 40 S&W in 10mm Auto??

MLC, do you shoot 40 S&W this way in a 10mm? Is it 100% reliable?

Hooks, a revolver would be fine since it is headspacing off the rim. On a semi-auto, it head spaces off the case mouth. That's why I was wondering if this would function out of it.
 
Re: 40 S&W in 10mm Auto??

Sorry, by cycle I meant chamber and fire.
I did it once, as I was told it would work.
I haven't made a practice of it but the Glock ran for a box of 40 cal Speer without a hiccup.
 
Re: 40 S&W in 10mm Auto??

A good friend of mine had a Colt Delta in 10mm and would pull out one of the recoil springs and shoot 40s&ws in it all day. He would practice with the 40s and carry the 10mms. He said he never had a problem, and all he used was factory ammo.
 
Re: 40 S&W in 10mm Auto??

The .40 cal case, when fired in the longer 10mm chamber, is held in place by the extractor.

Can't help but wonder how 10 mm cases ultimately chamber afterwards with the resultant accumulation of powder, copper and other residue from firing .40s previously.

I assume one has to clean aggressively, yes?

I've seen .357 cases hang up when attempting to eject them from cylinders with many rounds of .38 spl through them without significant cleaning.
 
Re: 40 S&W in 10mm Auto??

Funny you ask.

I have done this in my G20 and it "works" but pierces primers. Don't do it. The .40S&W case moves forward against the extractor, but still is held tight enough to fire, the primer kicks out of the pocket a little while the case expands in the chamber, then when pressure drops the case is slammed backwards, and the primer is slammed into the firing pin - piercing it and flattening it.
 
Re: 40 S&W in 10mm Auto??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cinosbus</div><div class="ubbcode-body">Funny you ask.

I have done this in my G20 and it "works" but pierces primers. Don't do it. The .40S&W case moves forward against the extractor, but still is held tight enough to fire, the primer kicks out of the pocket a little while the case expands in the chamber, then when pressure drops the case is slammed backwards, and the primer is slammed into the firing pin - piercing it and flattening it. </div></div>
This is what I would think would happen. I figured there were some guys out there who tried it. Thanks for the info.
 
Re: 40 S&W in 10mm Auto??

bet ya could buy a conversion barrel at a decent price rather than risk ruining your gun.
 
Re: 40 S&W in 10mm Auto??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300WSM</div><div class="ubbcode-body">bet ya could buy a conversion barrel at a decent price rather than risk ruining your gun.</div></div>

Where can I find a conversion barrel to shoot 40 S&W out of my G20sf?
 
Re: 40 S&W in 10mm Auto??

There a few barrels making making it. If your running the right recoil spring for real 10mm loads. Then you will need a new recoil spring to for the 40cal.

I dont what to post a non link so just google aftermarket barrels for glocks
 
Re: 40 S&W in 10mm Auto??

I have a 5.5" Federal .40S&W barrel for a G20 that is threaded with compensator I'll sell for $75. If you're interested, PM.
 
Re: 40 S&W in 10mm Auto??

Good luck getting one from Wolf, had one ordered for 4 mos, finally gave up, and cancelled it.
 
Re: 40 S&W in 10mm Auto??

I've seen 9mm a guy fired out of a G22. He brought them back saying it made his gun jam some and wasn't very accurate. The case was swelled to .40 diam at the mouth and the primers were pierced. Didn't hurt his gun at all, I told him he was very lucky.
 
Re: 40 S&W in 10mm Auto??

Works fine in mine. I think the prmer issue would come down to the extractor fitting on the individual gun.
I've shot a few boxes of factory 40, and maybe 500 rounds of light reloads. The light loads cycled, but just barely... the empties barely came out of the gun, and i'm of the impression that if the cartiges in the mag were forced against the front of the mag by recoil, and that 10mm length rounds would have been too long for the slide to pick up. still, it ran every time except when i let another guy shoot it and he limp wristed the first couple of rounds.
CW
 
Re: 40 S&W in 10mm Auto??

They run fine in mine. I did it as a test to see what would happen if there was an absolute ammo shortage and I absolutely needed to shoot SOMETHING from my 10mm G20

The accuracy at 25y was about a foot sized group from a gun that normally runs 2.25-2.5" for me. Certainly enough to hit an assailant, not enough that I am comfortable using it.

The case, as correctly stated above, is held in place by the extractor. They will not single feed, they must feed from the magazine. This practice is very hard on the extractor and will sometimes cause it to fail/break. Not necessarily during the firing of 40's either, several people I've heard of doing this have had it fail after another box of 10's was shot through it.

After 100 rounds or so I switched back to 10mms and saw no major changes in accuracy, POI, etc.

Lone Wolf has my 6" conversion barrel for them right now, I had some accuracy and FTF issues with it, their armorer has been very forthright in trying to fix it and work with me. If we can't figure out what's going on he said he'll just replace it. Be forewarned that he said they use pretty tight chambers on their barrels, and yes, they are fully supported. This is probably why I'm having some feeding issues, all the reloads and factory ammo I put through it were flat points.

LWD had no issues when I told Dan (armorer) that I was planning to shoot a lot of reloads, he even said to send him some ammo and he'll tailor my chamber to my reloads if I want.

The issue I did find with some 40 loads is that the light target WWB ammo won't generally run with the 21lb recoil spring I put in it. The stock spring (16 or 17# I think) runs just dandy.
 
Re: 40 S&W in 10mm Auto??

I've fired well over 6000 rounds of 40S&W in my one of my bone stock G20's.
Actually have done it in several that I have owned over the years.
I had one extractor break in a G 20 that I bought used, fired less that 50 rounds of 40 in it and had the extractor break while shooting 10mm's. My 10 loads are a bit above very warm tho.
 
Re: 40 S&W in 10mm Auto??

I think that you can do it in a Smith 610, Its shot with moon clips . I don's have the balls to do it in a G 20, Kimber , Wilson or A Delta.
 
Re: 40 S&W in 10mm Auto??

You can also put a 12GA shotgun shell in a vice, hit the primer with a hammer and make it fire too. It's just not advisable.

These auto pistols headspace by chambering on the mouth of the case, not by being held in place by an extractor.

Get you a 40S&W barrel and fire away.