I see a good bit of info that shows a .40 shooting thru a glock 20 with no apprarent issues.
First of all, does anyone have info that suggests that this is something that should not be done.

Second, assuming that it is reasonable to shoot .40 thru a 10mm for range only (I have a good bit of .40 and also can get it cheap thru a friend that remans ammo) so it seems like a way to practice and use up what I have around.....

What other guns works?  Sig 220?, Smith 1006?

To your first question, there are the manual(s) that comes with the gun, which state:

QuoteAlways be certain that the ammunition matches the caliber of your gun

https://us.glock.com/documents/The_Basic_Rules_of_Firearm_Safety.pdf

QuoteGlock recommends that you use only factory produced ammunition in good condition, and of the proper caliber for your pistol

https://us.glock.com/documents/Customer_Safety_Awareness_Form.pdf

Second, this article:

http://www.thegunzone.com/10v40.html

Now, lots of forum member are going to be along and tell me that I don't know what I am talking about, and that they do it all the time and never have any issues at all.  And I am sure that they are right, and more power too them.  This is still America, and they own the gun and are responsible for their decisions and I fully support them in acting according to their own will.

And, the Glock extractor is pretty beefy, and grabs a significant chunck of the case rim. Also, the firing pin mechanically cannot protrude more than about 1/8".  These two factors combined mean that it is very unlikely that the case will get knocked off the extractor by the firing pin, and therefore the case de-facto behaves like it is headspacing on the rim, not the mouth.

If you wanna do it, do a search here and you will find lots of threads of guys shooting 40 through the 10mm.  There are two active yesterday about a member loading to 10mm COAL in 40 S&W brass.

If the zombies were coming and all I had was a Glock 20 and 10K rounds of 40 S&W, I would load up and have at them.

So, is it suggested by reputable published sources, eg manufacturer instructions, gun industry authors, etc.  No, it is not a recommended practice, and is suggested that in some cases it may be dangerous.

Is your case and exception.  According to Glock, no.  According to other Glock owners here, yes.  Would I do it, maybe.  Have I done it?  No.

Are there other guns that work.  The Springfield Omega actually sanctions this activity due to the dual extractor design.  I would absolutely not consider it in my Witness because of how far the firing pin can protrude.

Good luck.

I tried it a few times, it work just fine.....  but why put the extractor under undue stress when a 40 s&w drop in barrel is about $100.

Quote from: tommac919 on November 11 2015 08:14:27 AM MST
I tried it a few times, it work just fine.....  but why put the extractor under undue stress when a 40 s&w drop in barrel is about $100.

This.

I wrote this yesterday for another member's post...

QuoteI have seen where many are loading the 40S&W cases as loaded at 10mm COAL's...Just as a side note the bullets can rub and roll up on the end of the chamber cut to leave carbon deposits and fouling.  This would need to be cleaned well before using the 10mm cases to prevent FTF stoppages as the longer 10mm casing encounters the last 1/8" end of the chamber.

If you are shooting 40's or 40's loaded as 10mm, they can foul that exposed 1/8" of chamber as noted above.  This is similar to shooting 38Spl from a 357Mag, trying to stuff the longer casings in that fouled space can and usually does make for them to stop short from chambering fully.  Cleaning is recommended for proper feeding before going to the longer brass cases. 

I do not recommended it, for the same reason everyone else does not recommend it. The manufactures recommend only using the cartridge for which the weapon was designed or intended. Therefore, you shouldn't do it.

That said, I do it with regularity (during target shooting, and the occasional spontaneous varmint), with multiple platforms (and calibers). Based on my own research, the "extractor stress" and long firing pin issues are, essentially, a myth (take it for what it's worth, from some anonymous internet personality), for several reasons. If the cartridge is presented properly in the chamber, case head against the breach, it will fire without risk or issue (chamber fouling notwithstanding). Newton (Sir Isaac) figured it out a long time ago. Primer dimpling is simply not enough resistance to overcome the mass of the cartridge as the pin strikes. Even with no extractor, fired cartridge cases didn't push forward the slightest measurable distance, when the case head was against the breach at the time of firing. This test was repeated several hundred times, and also included multiple platforms, autos with the extractors removed, held angled upward enough to rest the case head against the breach, and every other condition we could think up. Multiple primers were used, everything available from the "softest" small and large pistol primers, to the toughest large magnum rifle primers. Primed empty cases were also fired. Same result, every time, without variation. The condition simply didn't exist.

1/8" firing pin protrusion is LOOOOOOOONG. If your firing pin is extending 1/8" from the breach, your pistol is broken, or you have the wrong pin installed. Pin protrusion is typically less than 1/2 that, regardless of manufacturer or model. 10mm/.40SW case head thickness is less than .060", while most others, including large caliber pistol and rifle, are much less. If your firing pin extends past the extractor, no matter how "worn" it is, your pistol is broken or has the wrong extractor or firing pin installed. If your firing pin is able to contact the primer when the case head is ahead of the extractor, your pistol is broken and needs repair. If a round is chambered and missed by the extractor, it will simply be pushed forward in the chamber (with significant force/velocity), well out of the reach of the firing pin.

Also consider how straight-wall cartridges actually head-space. In almost EVERY case, it the case head, and not the case mouth. Chamber depth vs. minimum trim length demand it, rimmed or non-rimmed. Unless all your cases are trimmed to EXACTLY to chamber depth, they are head-spacing off the extractor or rim, or within that tolerance. If your extractor is not able to firmly hold the case head against the breach, it needs repair. If its tolerance is such that it allows the case to space ahead of the breach, it needs repair. The nanosecond case head expansion impulse force is greater than any force that may be applied by a pin strike. The remaining conclusion is, the extractor is "stressed" each and every time the pistol is fired, if that condition exists. If it were significant, in the least, you'd need to buy extractors by the dozen.

Any steel gun. Lee

Quote from: sqlbullet on November 11 2015 08:16:13 AM MST

Quote from: tommac919 on November 11 2015 08:14:27 AM MST
I tried it a few times, it work just fine.....  but why put the extractor under undue stress when a 40 s&w drop in barrel is about $100.

This.

If you can't afford the conversion barrel, sell some guns OR just don't do it.

Just checked my Witness Match....Extends .25"

1/4" extended from the breach, locked in battery? Something really wrong with that pistol. Broken or modified beyond safe. The Witness pistols I've 'smithed, including Match, were all within typical limits. None were anywhere near 1/4". Compare it with your others.

Both of mine are that way.  Not modified in any way.  Factory stock parts including the firing pin return spring.

That is curious. What is the length of the firing pin? 2.450 or 2.590"? It's been a while but I think this had something to do with failing to pass CA's drop list. They still haven't, to my knowledge.

2.590".  2.620" was the measurement from firing pin stop to breech face, and I didn't have to push them in 1/2" before anything appeared.


 

O K  They recommend not doing it.............I have seen Glocks, Colt's, Para's, Dan Wessons, Witness's, Kimbers......shoot 40's out of 10mm barrels.  All stock guns, did not ever run in to a problem with it....

I was more curious than anything else;   I have a Smith 1006, just curious about the design that allowed glock to fire