.40S&W in a 10mm........

[Pablo]

Don't shoot the messenger.

I had never, even, ever considered chambering a .40S&W in a 10mm gun. I have been reading some typical 10mm info on the 'net about 10mm, case bulging, hot loads, platforms, etc....then I come across these guys that shoot .40S&W all the time in (mostly) Glock 20's and 29's. But some 1911's. I was a bit shocked. Some laughed off the warnings, others said the worst thing they had were punctured primers........

Thoughts? Experiences??

I'm not planning on doing this. This is NOT the purpose of this thread. I just want get a more rational, intelligent, dare I say SANE viewpoint.

[Bill_in_Utah]

Take a .40 S&W and take out your Glock 20 barrel. Drop the .40 into the 10mm barrel and see what happens.

While I've never done this I'd think that since they both head space the .40 S&W will drop WELL into the chamber and no firing pin would reach it. The 10mm into a .40 chamber quite a bit of the round would be sticking out of the .40 barrel.

I think the only way people are shooting the .40 S&W in their Model 20/29 firearms is with different (read .40 S&W) barrels in the frames.

Just my 3 cents.

Bill

[Pablo]

I'll do exactly that, later today after I get back from shooting.

They specifically said they did not have .40 S&W conversion barrels in their Glock 20/29's.

Exactly why I'm saying what the heck. Maybe "It's the interweb"

[Bill_in_Utah]

I'll do exactly that, later today after I get back from shooting.

They specifically said they did not have .40 S&W conversion barrels in their Glock 20/29's.

Exactly why I'm saying what the heck. Maybe "It's the interweb"

Here is a company that does offer .40 S&W and .357 sig barrels for the Model 20.

Here are the same for the Model 29.

Interesting to find out what you find out.. (did that make sense?)

Take care and be safe shooting!

Bill

[Pablo]

Originally Posted By: Pablo

I'll do exactly that, later today after I get back from shooting.

They specifically said they did not have .40 S&W conversion barrels in their Glock 20/29's.

Exactly why I'm saying what the heck. Maybe "It's the interweb"

Here is a company that does offer .40 S&W and .357 sig barrels for the Model 20.

Here are the same for the Model 29.

Interesting to find out what you find out.. (did that make sense?)

Take care and be safe shooting!

Bill

OH I know they make conversion barrels. I have a 6" .357Sig barrel for my Glock 20.

http://www.lonewolfdist.com/Detail.aspx?PROD=947&TERM=LWD-20L357

Point is the guys said specifically they were NOT using conversion barrels.

[Bill_in_Utah]

Understood.

I'll be interested to see what happens with the little experiment with the .40 S&W round into the 10mm barrel.

Take care!

[BarryinIN]

I would GUESS the case dimensions would be close to the same at the areas the .40 case would sit in the 10mm chamber, based solely on the fact reloading dies are interchangeable.

The problem I can first think of is headspace. If the .40 would seat too deep it wouldn't fire. The Glock extractor might hold it in position though, since I know most .40 Glocks will chamber and fire a 9mm round because I saw it demo'd in a Glock armorer's class. Don't so this at home, etc and so on. In that case, the extractor held the 9mm case against the breechface to fire (and split) the case. One of the points was to show how well the extractor worked and that you could get by with a .40 extractor in a 9mm if it's all you had.

Whether that tanslates to a 10mm extractor holding a .40 I'm place well enough, I don't know.

Glock has changed extractors so much in the 9/40s that I don't even know if it still holds true there. I wouldn't be a bit surprised if they stopped doing that little demo now, for obvious reasons

Max pressure is actually slightly less in the .40 than the 10mm (35,000 psi and 37,500 psi) although the smaller .40 case is more susceptible to pressure rises from bullet setback- which you might get if it has a less smooth route to the chamber when fed from a 10mm magazine.

[Pablo]

The .40 butt end sits flush with the Glock barrel. There is no way the firing pin would reach the primer, so it must be held in place with the extractor. Obviously not a good situation!

[G-MAN]

I think this is a bunch of baloney circulated by people who don't understand how these cartridges headspace. They think you can shoot 38 Special in 357 Magnum, and everyone knows a 38 is just a shorter 357, so if a 40 is just a shorter 10mm, voila! 38s and 357s headspace on the rim, but the 40 and 10mm are rimless and headspace on the mouth. Hence, as you saw, if you try to chamber a 40 in a 10mm gun, the round just sinks into the chamber with the primer well out of striking distance.

[Bill_in_Utah]

I would GUESS the case dimensions would be close to the same at the areas the .40 case would sit in the 10mm chamber, based solely on the fact reloading dies are interchangeable.

The problem I can first think of is headspace. If the .40 would seat too deep it wouldn't fire. The Glock extractor might hold it in position though, since I know most .40 Glocks will chamber and fire a 9mm round because I saw it demo'd in a Glock armorer's class. Don't so this at home, etc and so on. In that case, the extractor held the 9mm case against the breechface to fire (and split) the case. One of the points was to show how well the extractor worked and that you could get by with a .40 extractor in a 9mm if it's all you had.

Whether that tanslates to a 10mm extractor holding a .40 I'm place well enough, I don't know.

Glock has changed extractors so much in the 9/40s that I don't even know if it still holds true there. I wouldn't be a bit surprised if they stopped doing that little demo now, for obvious reasons

Max pressure is actually slightly less in the .40 than the 10mm (35,000 psi and 37,500 psi) although the smaller .40 case is more susceptible to pressure rises from bullet setback- which you might get if it has a less smooth route to the chamber when fed from a 10mm magazine.

[Ursae_Majoris]

Pablo, it can be done, I've seen it done. Extractor will hold cartridge in place. Do I recommend it? No.

As far as cartridge splitting if unsupported, remember smiley faces at 6 o'clock in factory 40 S&W Glock barrels? I load at 90% percent of handbook (nosler and speer) and never had smileyes.

I suspect a mild factory load (non-Corbon) with a lighter bullet (135 gr to 155gr) will, at most, cause a slight bulge all the way around, but won't split the case. Hot 180 gr factory load, or a handload with 200gr is another matter. Mr. G. will become a hand grenade.

[NavyVet1959]

I have shot quite a few .40SW rounds in a 10mm barrel in a Glock 20 and Glock 29. The extractor holds the round more securely than with a M1911 style handgun. A better solution though is to use .40SW brass and reload it to 10mm overall length so that you can load it to full 10mm pressures / velocities. It won't chamber in a .40SW handgun at that point, so you're in no danger of accidentally loading it in a firearm that is not built for that pressure.

[Pablo]

Thanks NavyVet! Thanks for your service!!

What you write makes sense. And I have read about others doing this.

I now have a new Glock 20SF (and a .40S&W Barrel) plus I scored a HiPoint 4095 Carbine!

[NavyVet1959]

Thanks NavyVet! Thanks for your service!!

What you write makes sense. And I have read about others doing this.

I now have a new Glock 20SF (and a .40S&W Barrel) plus I scored a HiPoint 4095 Carbine!

Not all .40SW barrels will allow you to load to 10mm lengths though. If not, then you can get the throat reamed to 10mm length. There's a guy on one of the forums that I frequent that does it rather reasonably.