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Discussion Starter #1
I am curious if it would be possible(though of course something you would not want to do), to fire a .40 cal round thru a barrel chambered for 10mm?

I would think you would be able to do so, just like firing a .22LR in a .22 Mag barrel.
 

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The .40 and 10mm, unlike the 22LR and WMR headspace on the cartridge mouth.

While you can load a .40 into a 10mm chamber, firing it would be most unsafe. I've seen pictures in Patrick Sweeny's 1911 book that show a blown case - not a good thing.

Don't do it.
 

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Firing a .22 in a .22 Mag chamber isn't too bright, either.

It is NOT like shooting a .38 in a .357; the chamber diameters are different. The result is a split .22 case, hot gases going where they were not designed to (with all the consequences thereof, rapid leading of the chamber if the practice continues, and a slow bullet coming out the muzzle.

So, just what is the UP side? :hrm:
 

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I have seen a guy fire 40 S&W cartridges through a 10mm barrel. Seems like the extractor would hold the base of the case close enough to the breachface that the firing pin could get to it. The bullet must have made a "leap of faith" from the case mouth to the bore.
 

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Hey, I've seen guys shooting 9mm through a 40 cal. pistol so I'm pretty sure it would fire in the pistol. I would imagine the edge of the chamber would be scraping jacketing from the bullet and getting a buildup of copper there pretty quick too. Would not be doing it unless there was no other alternative.
 

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Possible, yes.
Practical, depends on the firearm. The S&W M610 revolver uses moonclips which allows the interchange between 10mm and .40SW.
 

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Here we go again. In a S&W M610 that uses half moon clips, yes. In a chamber that head spaces on the case mouth, no. The 40 S&W is .003 smaller in diameter and will slip forward or is driven forward in the chamber when hit by the firing pin. This leaves the cartridge base unsupported. The primer can setback, leak or even blow out allowing high pressure gas to escape rearward. Not a good thing. Bob http://www.thegunzone.com/10x40.html
 

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I misquoted the article I read. The 40 S&W is .03 mm narrower in the web area, not in case width. The widths only differ by .001. The shorter 40 S&W case will try to headspace on the case mouth and can still be fired in the S&W M1076 that was the test bed. Maybe other autos too. Bob
 

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Bob,
With the .40SW case being .142" shorter than a 10mm case, and headspacing on the case mouth it will be too short for a firing pin strike in a 10mm chambered barrel.
The only hope is that it headspaces by the extractor hook.
 

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It would fire in the S&W M1076. Quite nasty. The cartridge may not go all the way forward or may come out from under the extractor, I don`t know. The article I read is at the bottom of the page of the link I posted. Bob
 

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I hate to get dogmatic here, but I like the simple approach of shoot ammo in the gun for for which it is chambered.

Gun chambered in 45ACP? Don't try shooting 400 Cor-bons.

Gun chambered in 9x23? Dont try shooting 38 Supers in it.

Gun chambered in 10mm? Don't try shooting .40 in it.

If you want to shoot .40, buy a gun or barrel specifically for it. If the gun were to go bang the "wrong way", you'll feel like a horse's ass if the gun or you is damaged.

With all due respect, I wouldn't take a lot of stock in internet gurus saying you can shoot all kinds of different combos.
 

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In a S&W 610 revolver using half moon clips, yes. In an auto that head spaces on the case mouth, no. In a S&W 1076 auto according to what I read the firing pin has enough travel to fire them but the primers perforate or blow out causing hot gasses to escape toward your face. Bob
 

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Heck, if you are going to shoot 40 down a 10mm, why not ask about shooting the 357sig down the 10mm?

Would it work, ie: projectile out of the bore? Yes, probably, but you have opened yourself up to a bunch of issues like:

Headspace,
Chamber support
Buggering up the leade on the barrel
Etc.

As a 10mm fan, I have to ask why you would consider it? Think about the consequences of if the cartraige KB-ed on you and for the rest of your life you go around to the gun stores like this.

"Say Fred, how you get your shooting hand all scarred up like that?, and before you can say it was an old "war-wound" one of the regulars says, oh thats just ol' "40 fred" and everyone laughs....."

ps: shooting 22lr in a 22 mag is not a good idea either. Check the dimensions of the cartraige.....
 

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SO SUE ME FOR HEADSPACE

I've fired 9x19 in a 41AE barrel; I like extractors.

Can; yes.

Should; no no no.
 
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