40sw in a 10mm?

[badwolf]

Can and should 40sw be fired in a 10 mm pistol?

[Bigslug]

Can? Maybe. . .sometimes. . .

Should? No.

It's a straight, rimless case that is toleranced to be anchored in place for firing between the breechface at the rear, and the case mouth at the front. A 10mm chamber is too long to allow this to happen, and you end up relying entirely on extractor grip on the case groove to hold the case in place where the firing pin can actually hit the primer.

This is not the .38 Special/.357 Magnum scenario in which headspace is established by the pronounced rim which stops forward movement in the chamber. The back end of a .40 is the same width as the front, and it'll try to go forward in the hole until the hole gets smaller.

[pete501]

A fella at the range was shooting 40sw out of a Glock 20 10mm with no malfunctions. He said the extractor was strong enough to hold the cartridge in place. It seemed to work so I tried it with my G-20. It may depend on the firearm.

[Lloyd Smale]

wont hurt a thing. ive done it reliably in my 20 and 29. like was said your basically head spacing with the extractor so worse case is you get light primer strikes. only thing that might come back to bite you is if you do it alot your going to get hard to remove crud in your chamber that might cause reliability problems when you go back to tens

[truckerdave397]

My 610 Smith loves them both.

[rockshooter]

An issue I encountered I think was related to the mass of the Glock 20 slide- the 40 cases kept hitting me in the head!
Loren

[contender1]

Since you said "pistol" I'm assuming you are referring to a semi-auto firearm.

I can shoot .40 S&W in my revolvers easily. I use moon clips if the gun needs them.

In a pistol,, as noted,, they headspace off the case mouth,, and it may work, and it may not. If the extractor can hold the brass well enough to allow for the primer to ignite,, there won't be any issues with the bullet fitting the bore or whatever. But as noted above,, the crud build up in the chamber may become an issue.

[atfsux]

About 10 years ago I discovered quite by accident how the Glock 20 can eat .40S&W ammo like it was made for it.

I went to Cabelas to get a few boxes of 10mm ammo. I found the Winchester white box stuff on the shelf and grabbed 3 boxes. What I didn't realize at the time was that whomever stocked the shelf made the mistake of adding some boxes of .40S&W to the same pile. I read the end flap of the box I saw,...then grabbed it and 2 others, not realizing they were actually .40S&W.

So I get to my remote shooting spot only to at that point discover what I actually had; 1 box of 10mm and 2 boxes of .40S&W.

I didn't want to waste my time on my trip out to this hard-to-get-to spot by just blasting through a single box, so I decided to use up the .40 ammo as single-shot accuracy practice. I loaded the 10mm mags with the .40 fodder, not expecting the gun to cycle and feed. I expected jams,...and would then clear manually and jack the slide to load a new round. I was absolutely stunned and amazed when the ammo both fired, cycled and fed reliably without issue. The only potential problem was that the pistol was piercing the small primers on the .40 brass. But that merely added a little bit more carbon to clean up later and didn't impede function in any way.

Back during the last great ammo shortage of around that time, .40S&W was the first caliber that began to recover and become available, long before .45 or 9mm or .223 or .308 or 7.62x39. And I had previously bought a Glock 23 specifically to buy a 9mm conversion barrel for, rather than buy a G19, just to ensure I had 2 calibers as an option in some potential sad future. I was absolutely tickled to realize that my G20 had essentially come from the factory chambered in 2 calibers and didn't even need to buy the extra barrel.

I don't shoot .40 through the G20 on any sort of regular basis because I don't need to and I prefer the 10mm. But it is always a hoot to brag to other shooters that my 10mm can shoot .40 without modification,...and then they bet money on it that I'm full of it. No sweeter victory than free money!!

[Bmi48219]

Can and should 40sw be fired in a 10 mm pistol?

Sounds like a question for the BATF.

[Lefty Red]

In Glocks, yes nothing wrong with shooting 40SW in their 10mm. I’m fact, I carried a G20.3 on duty and used 40SW for a few years until I got a G22 for duty. Also shot that same G20.3 in competitions using 40SW. Only shot 10mm for deer season over in SEMO and also hogs. Just a change of RSAs was all it took.

I just got the newer G20.5 MOS and it’s only has one mag of 10mm **** through to. Rest have been 40SW.

Jerry

[Castaway]

Lefty Red, what’s an RSA?

[Recycled bullet]

Sounds like a question for the BATF.

Careful they'll shoot your dog.

[Outer Rondacker]

wont hurt a thing. ive done it reliably in my 20 and 29. like was said your basically head spacing with the extractor so worse case is you get light primer strikes. only thing that might come back to bite you is if you do it alot your going to get hard to remove crud in your chamber that might cause reliability problems when you go back to tens

Lloyd Smale's is correct. I have many rounds down the pipe of my 29 and works just fine. But for legal reasons I say only shoot factory ammo meant for the gun.

[1006]

I shot a lot of 40’s in a Colt Delta Elite without issue, before re-barreling. I did find that I needed 40S&W mags to make it reliable.

As it happened, the gun had a poorly fit factory barrel…..neither 10, nor 40 was accurate enough for target shooting.

I had two replacement barrels fit, a 10 and a 40. I seldom use the 10mm barrel.

[Dusty Bannister]

Lefty Red, what’s an RSA?

Do you mean "Recoil Spring Assy"? Creative acronyms for an international forum?

https://castboolits.gunloads.com/sho...62#post5605362

[Bill Allen]

I'm confused (nothing new there) but why shoot basically the wrong bullet out of your pride and joy?

[rockshooter]

why shoot it?- cheaper and far easier to find. Used to be that .40 brass was lying all over ranges- now not so much but still around. 10mm brass is rare.
Loren

[Lloyd Smale]

Lloyd Smale's is correct. I have many rounds down the pipe of my 29 and works just fine. But for legal reasons I say only shoot factory ammo meant for the gun.

actually it works better in my 29 than it does in my 20. i get occasional misfires with the 20. I said it can be done and it can but id never load it with 40s to carry for protection or to protect my family

[Lefty Red]

Lefty Red, what’s an RSA?

Sorry, it’s what Glock calls their recoil spring RSA=Recoil Spring Assembly. For heavier hunting loads I used an aftermarket one so I could adjust the poundage.

[roysha]

I'm confused (nothing new there) but why shoot basically the wrong bullet out of your pride and joy?

The bullet is just fine, it's the length of the CARTRIDGE case that is moving the conversation.