[BruceO]

You also erode the shoulder in the chamber, among other things. The only bad things are not just the possibility of a catastrophic failure although that may be sole concern of some.

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

[dm1906]

Originally Posted by BruceO

You also erode the shoulder in the chamber, among other things. The only bad things are not just the possibility of a catastrophic failure although that may be sole concern of some.

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

Erosion is no more likely than with any other cartridge, correct or not. And the article does not refer to Glock pistols. We've repeated, over and over again, this should not be tried in any other brand pistol. I'm NOT trying to convince anyone to try anything they are not absolutely comfortable with, or that may be unsafe. Only trying to dispel myth and rumor regarding THIS situation. The Glock doesn't know the difference, nor does it care. A .40 round won't fire (any more likely than if it were a 10mm round) if it's isn't properly chambered (either would be equally bad). Other pistols, such as those in the article, may. If the Glock does, it was already broken, or modified in such a way this should never be attempted (such as an extended striker, which is a bad mod, in almost any case).

[BruceO]

Erosion is no more likely than with any other cartridge, correct or not. And the article does not refer to Glock pistols.

Yah, right.

It doesn't mention the Glock by name because it's a general statement.

Anyway...................

[Yondering]

It's funny how some people will argue against doing this, despite all logical explanations, without having a clue what they're talking about. If you don't understand why this can be done in a Glock but shouldn't be done in other pistols, fine, but quit acting like you're smarter than the rest of us - you aren't. Open your mind and look at the facts, and quit going off old rumors.

Throat and chamber erosion is no different firing 40 vs 10mm - it's practically non-existent with either round; these aren't magnum rifle rounds with large powder volumes and small bores.

[Javelin]

Originally Posted by Yondering

It's funny how some people will argue against doing this, despite all logical explanations, without having a clue what they're talking about. If you don't understand why this can be done in a Glock but shouldn't be done in other pistols, fine, but quit acting like you're smarter than the rest of us - you aren't. Open your mind and look at the facts, and quit going off old rumors.

Throat and chamber erosion is no different firing 40 vs 10mm - it's practically non-existent with either round; these aren't magnum rifle rounds with large powder volumes and small bores.

Yeah because that extra 3mm of brass on the 10mm casing and barrel chamber is just there for aesthetics anyway......

[dm1906]

Originally Posted by BruceO

Yah, right.

It doesn't mention the Glock by name because it's a general statement.

Anyway...................

Right. It is/was a general statement, general to the pistols examined, which didn't include Glock. The reasons for the failures they describe are not characteristic of the function of a Glock pistol. I/we do not recommend this practice in pistols other than Glock for the reasons they describe. Please provide a source describing a Glock failure, under these conditions. If it's happened, it's a big secret.

[Ebb27]

Originally Posted by copo9560

I have tried the experiment and had no issues - maybe I was lucky. Better question is does anyone have any documented proof of a G20 blown up by using 40S&W? I can see beating up the extractor but that is easy enough to change. There appear to be a lot of guys trying this - curious if anyone has really had a bad experience.

Well I know a lot of folks like drama but both rounds are similiar CUP pressure with the 10mm being a bit higher.

So it's not likely you're gonna get some catastrophic failure that causes the pistol to blow-up like a pipe-bomb by using a shorter lower pressure round.


At most you'll damage the extractor, or the round will slip past the extractor and fail to fire.

[Spring Hill Glocker]

Someone make a YouTube video about this maybe moss pawnshop channel will do a special I do know you can buy caliber inserts for a 12 Gauge and shoot 9mm 22lr 357 out of it safely but I can't comment on the accuracy but if it comes down to you finding assorted ammo and only a shot gun these inserts would be a heaven send in a crisis.

[ithaca_deerslayer]

Cool thread.

Maybe reason enough to buy a 10mm now

[vaquero aleman]

I'll up your ante,

I have a G21, in which I placed a factory G20 6" barrel, and fired some 40 S&W. I use a Wolff guide rod with #20 spring. I shot Underwood 165gr 40 for a few rounds and then tried some Underwood 135gr 40. I threw away the first three rounds, of the 135gr, because they did not ignite. The pin had obviously punched the primer but did not ignite it. The 165gr fired without incident but the 135gr would not fire and I can only assume it was because the extractor could not hold the case against the breech solidly enough. Therefore, I intend to get a 10 to 40 conversion barrel to use in my G21. And I did perform the "KKM" mod to the extractor.

And, I must add, that there is no "why" only "just because".

[Slateman]

So I can shoot .40S&W, no problem with stock barrel and mags?

[vaquero aleman]

I loaded the 40 into factory G20 mags, which of course fit in my G21 because the frame is the same as the G20, and other than a little sliding back and forth in the mags, of the cartridges, there appeared to be no problems. Of course these are just my results.

I am in no way warranting the use of 40 S&W in a Glock 20 or 21, it is a personal choice. Do so at your own risk.

And don't tell Gaston about it, they are kinda fussy about those things.

[gofastman]

Can .40 be shot out of a stock 10mm EAA Witness?

[Any Cal.]

Look at it and see. You want to be sure that the firing pin can't hit the primer if the case is ahead of the extractor, which would allow the gun to fire out of battery. You also want to be sure that the extractor is heavy enough to take the force of the firing pin strike repeatedly. I have heard of one person who did what you are suggesting, but have no experience at all with that pistol, so could not say whether it is safe or not.

[Yondering]

Originally Posted by gofastman

Can .40 be shot out of a stock 10mm EAA Witness?

It is not a good idea. Just like a 1911 and most other 10mm pistols, the firing pin is long enough to set off the round, even if it is in front of the extractor. This causes the case to slam back against the breech face, and sometimes results in case bulges and possibly ruptures. You'll also notice a spot where the case rim gets sheared off, as it's forced past the extractor (towards the rear) at high speed.

The Glock is the only gun I know of where this is a safe practice.

I will admit to doing this with my Witness back when I had one, to find out what it would do, and have never seen or heard of damage to a gun or shooter from it, but just judging from the appearance of the brass, I wouldn't do it any more.

In the Witness, when (not if) a round jumps the extractor, you'll see fired brass like this:

[RMM]

Just thought I'd stop in and report my experience.

Gun: Gen 3 G20SF (2012), stock barrel, stock recoil assembly.
Ammo: Federal Champion 40 S&W, PMC 200 gr. 10MM.

Was shooting at a ~8" bullseye target at 10 yards. All rounds chambered and fired without any problems. However, the accuracy seems to have suffered significantly. I fired 10 rounds of 10mm, all rounds grouped ~3". I then shot 10 rounds of the 40 S&W, all rounds hit ~4" lower than the 10MM rounds and had an ~8" group. Thinking that I was probably just nervous, I put out a new target and tried again. 10 rounds 10MM, followed by 10 rounds 40 S&W. The results were similar, I didn't see any keyholing but the grouping was definitely low and loose.

Nice to know that the 40 S&W will work in a pinch with the stock barrel, but I'm not going to make a regular practice out of it.

[Bren]

Originally Posted by glock_19guy1983

This. 10mm headspaces on the case mouth, running a 40S&W case in a 10mm chamber means that the extractor is the only thing holding it in.

Yep, it will work until it doesn't. I'm not sure, but I would think it could result in the case head separating and some brass and crap blowing out of every hole, sooner or later.

[ScottieG59]

It is not difficult to use a conversion barrel. I use a Lone Wolf 10mm-40S&W conversion barrel and the original 10mm mags.

[Grizzz]

Sooo your saying i can get a g20 / 10mm conv. to 40s&w & shoot it in my g21 slide ?

Originally Posted by vaquero aleman

I'll up your ante,

I have a G21, in which I placed a factory G20 6" barrel, and fired some 40 S&W. I use a Wolff guide rod with #20 spring. I shot Underwood 165gr 40 for a few rounds and then tried some Underwood 135gr 40. I threw away the first three rounds, of the 135gr, because they did not ignite. The pin had obviously punched the primer but did not ignite it. The 165gr fired without incident but the 135gr would not fire and I can only assume it was because the extractor could not hold the case against the breech solidly enough. Therefore, I intend to get a 10 to 40 conversion barrel to use in my G21. And I did perform the "KKM" mod to the extractor.

And, I must add, that there is no "why" only "just because".

[vaquero aleman]

I don't see why the 10mm to 40 conversion barrel wouldn't work, but I am not an expert or gunsmith. I very well intend to get a conversion barrel for my 21. I would rather have it and not need than the other way around. 40 S&W is easier to find than 10mm for sure. And, in most cases, cheaper. I picked up a 100 round value box of Rem 40 at walmart when everything else was sold out.

[Grizzz]

The reason i ask is i have a g21 / 10mm storm Lake barrel & i couldn't find a g21 / 40 s&w conv. barrel. I don't think they make one, at least Storm Lake dosen't.

[vaquero aleman]

Originally Posted by Grizzz

The reason i ask is i have a g21 / 10mm storm Lake barrel & i couldn't find a g21 / 40 s&w conv. barrel. I don't think they make one, at least Storm Lake dosen't.

I have to agree, I don't think that a 45 to 40 conversion exists but I will be buying the LWD 10 to 40 conversion when they finally get it in stock. $109 plus shipping is a whole lot cheaper than another gun.

And, I finally got some Underwood 180gr TMJ 10mm and that is what I am now carrying in my 21. I have some questions to be answered about my slide before I continue shooting .460 Rowland. I should be getting about 1425 to 1450 fps from my 6" barrel. Pretty hot!

[ScottieG59]

Originally Posted by vaquero aleman

I have to agree, I don't think that a 45 to 40 conversion exists but I will be buying the LWD 10 to 40 conversion when they finally get it in stock. $109 plus shipping is a whole lot cheaper than another gun.

And, I finally got some Underwood 180gr TMJ 10mm and that is what I am now carrying in my 21. I have some questions to be answered about my slide before I continue shooting .460 Rowland. I should be getting about 1425 to 1450 fps from my 6" barrel. Pretty hot!

Well, you will need some magazines. The 40S&W, 357 SIG and 9x25 Dillon will feed in a Glock 20 10mm magazine. I would not trust the 21 magazine to be reliable with those calibers.

I also wonder how reliable the extractor would be. The 10mm Glock 20 conversions I see all have the same base diameter. It may work fine like my Glock 27 40S&W-9mm conversion, in which I change the barrel and use 9mm magazines.

[vaquero aleman]

I got two G20 mags when I bought the 6" barrel. And after I shot the 40 I found that I had to do the "KKM" conversion on my extractor. I shot some 10mm after that and everything was ok, but I haven't had a chance to run any more 40 through it. Also, it's not as positive an ejection as the 45 but the 40 does eject when I cycle some by hand.

But, to get back to the OP's point, I did pick up a value box of Rem 40 S&W JHP that I intend to run through my factory G20 6" barrel. I want to see if the mod to the G21 extractor will fix the ejection problem with the 40 caliber rounds. And I need to see if maybe their might be a problem with the Underwood 135gr primers being a little too hard.

[Billy10mm]

Originally Posted by Yondering

It is not a good idea. Just like a 1911 and most other 10mm pistols, the firing pin is long enough to set off the round, even if it is in front of the extractor. This causes the case to slam back against the breech face, and sometimes results in case bulges and possibly ruptures. You'll also notice a spot where the case rim gets sheared off, as it's forced past the extractor (towards the rear) at high speed.

The Glock is the only gun I know of where this is a safe practice.

I will admit to doing this with my Witness back when I had one, to find out what it would do, and have never seen or heard of damage to a gun or shooter from it, but just judging from the appearance of the brass, I wouldn't do it any more.

In the Witness, when (not if) a round jumps the extractor, you'll see fired brass like this:

For the record, I shoot .40 out of my 10mm 1911 frequently.