Glock 20

[Intel0116]

Someone mentioned to me that you could use .40 S&W rounds in a glock 20 (10mm) with out issue.

is this true? if so I think I found my next purchase

[Lumpia is sarap!®]

You will need a conversion barrel.

[Intel0116]

You will need a conversion barrel.

I was told you could use the same barrel and clips. basicly no modification needed.

[mcmikeblues7]

I was told you could use the same barrel and clips. basicly no modification needed.

You were told wrong.

[Intel0116]

http://www.youtube.com/watch?v=AwXtEm70Q0M

how come this guy can do it ?

[Cool Custard]

http://www.youtube.com/watch?v=AwXtEm70Q0M

how come this guy can do it ?

Magic!

[Intel0116]

Magic!

lol

[SILENT GUNMAN]

I shot an idpa match with mine running .40s without any issues a couple months ago. Its not going to hurt it any more than shooting .38s out of a .357 mag. Just make sure you clean the chamber before you put 10mm in it again and it'll be fine. Buying a .40 conversion for a 10mm is a huge waste of money. If you want a conversion barrel get a 9x25 Dillon barrel and you'll be able to shoot 3 different calibers out of one gun. The ability to run .40s or 10mm without modification is one of the reasons I got mine in the first place.

[hcbr]

Intel0116, if I were you, i'd just be careful, and aware, yes, you can do it, and yes i've heard it before, but remember, they've engineered the gun based on the ammo and the size/dynamics

Shoot at your own risk, but my advice is to just have a conversion barrel and have 40 mags handy. That or just buy a 22 altogether lol

[Dark Mod]

there are members on here who do it all the time. Ive done it once or twice to test the issue and have had no problems.

I think it was XDrox whos been doing it religiously

[gsparesa]

Why would you want to do this? Ignoring safety rules is asinine. Why load anything else then what's stamped on the barrel? The headspace is different between both calipers. The rim has got to be slamming the breach when the gasses expand and bullet has to be wearing the rim of the throat trying to get centered. Not smart!

[JeremyS]

Someone mentioned to me that you could use .40 S&W rounds in a glock 20 (10mm) with out issue.

is this true?

YES, it's true.

IMHO, the people on here saying you cannot or should not do it are speaking based on assumptions and not knowledge or experience. I completely agree with SILENT GUNMAN, and I'm sure soon enough some of the extremely experienced and knowledgeable Glock guys like Ocean Bob will weigh in as well.

The truth is that this thread could probably go 20 pages of people arguing theories and engineering diagrams and physics and "what about" and blah blah but the TRUTH of the matter, in practice, is that many people have put literally hundreds or thousands of rounds of .40 S&W through their 10mm Glock with NO issues whatsoever at all. No wear to the chamber, throat, extractor, breech face, etc. NOTHING out of the ordinary at all, whatsoever. And YES, you can do that, too. And then people will come in and say "well maybe you can, but that doesn't mean you should" and fine... whatever. The fact of the matter is that it's safe and it actually works fine and it isn't going to hurt your gun and it isn't going to hurt you. It shoots straight and it'll save you $$$ so if you want to shoot .40 through your 10mm Glock then go nuts.


I can't believe you actually found and posted my video! That's hella cool. I shot this after putting hundreds of .40 through my G20SF myself and I have personally seen guns with many many more through than that. Other CalGunners, I'm sure, are going to weigh in and tell you that they have done the same.





This is fairly similar to running various length calibers in a revolver (or lever action, etc). The difference is, of course, that revolver calibers head space off the rim rather than the lip of the brass. In the case of .40 S&W out of a 10mm, the extractor holds the round against the breech face. gsparesa's scenario really does not happen. The round is centered because the brass is in the chamber and the chamber does not have much wiggle room. That's one reason why the bullet isn't wearing the throat. And again, it really isn't practically different in this regard than a revolver where the bullet travels an even longer distance between the cartridge and the barrel/rifling (and even passes through a gap and a forcing cone).

my advice is to just have a conversion barrel and have 40 mags handy.

Dude. The G20 is a large frame Glock and the G22 is a small frame. The .40 mags wouldn't work in the G20. Even with a conversion barrel, you must continue to use the G20 magazines. Come on... you are giving advice in this thread with no experience on the specific subject. Also see below, RE engineering a gun for a more powerful cartridge and being able to run a bunch of less powerful cartridges through it.

...and RE gsparesa's "why load anything else than what's stamped on the barrel?" you must realize that there are dozens of examples where that is perfectly fine, such as .44 special out of a .44 magnum or .38 of a couple types out of a .357 or .22 short/long/long rifle or .32 S&W, .32 S&W Long, and .32 H&R mag out of a .327 Federal Magnum. No, the barrels typically don't have all of the acceptable calibers marked. Just the largest or 'primary' caliber. Sure, maybe you'll say "well that's okay in a revolver or a lever action or a bolt action in some cases but not in a semi-auto." Well... here's an exception to what would normally be a perfectly legit rule to live by. .40 S&W is a shortened 10mm and that 3mm of overall length difference and lower pressure and power level doesn't cause issues. .40 will feed, fire, extract, and eject out of a completely and totally factory stock Glock 20 or 29 with NO problems whatsoever at all in any way. Sorry, it just works.

[Intel0116]

lmao, that was your video. small world. well after reading what you had to say it does make sence to me know. why wouldent a shortend and less powerfull round work in a gun that was built to handle its more powerfull counter-part.

[JeremyS]

Normally you might expect it not to be strong enough to cycle the action, but it doesn't have that problem with the Glock. Part of that may be that the 10mm round varies greatly in power level from right about .40 S&W power level to much more than that. That's no coincidence, either, if you know some of the history of where the .40 came from...

The FBI chose 10mm when it wanted a more powerful round. They then decided it was too powerful because the recoil was hard for some agents to handle. So companies like Federal started downloading the 10mm to a lower power level. At this point, S&W figured why use these larger guns and long rounds when the case capacity isn't needed anymore, and they shortened the 10mm by 3mm and called it the .40 S&W. Now they were hitting FBI-10mm-power levels but in a shorter cartridge that could fit in 9mm-sized guns. .40 S&W literally uses the exact same bullets, and the cases are identical except for two changes -- they're shorter by ~3mm and they use a small pistol primer instead of a large pistol primer.

Anyway there's still lots of 10mm on the market that is loaded to FBI 10mm spec, not true 10mm spec. The Glock is designed to work with all of it and therefore it handles .40 S&W power levels just fine.

For instance, check out Federal's Hydra-Shok in 10mm vs. .40 S&W... 180 grain 10mm = 1,030 fps muzzle velocity, and 180 grain .40 = 1,000 fps muzzle velocity (same stats for their American Eagle 180 grain offerings).



Some commenters on the YT video thought that .40 would be all over the dang place when shot out of a 10mm, and that really isn't the case. I've only tested it back-to-back once and only with the factory barrel, and the results can be seen here:

[Sam Z]

I love my Glock 20
It is THE most versatile platform in existence!

The following calibers are possible with a simple barrel swap (I prefer to have conversion barrel for .40 S&W)

.40 S&W
9x25 Dillon
.357 SIG


The following calibers are possible with conversion kits (slide & barrel)
.50 GI
.22 LR
.45 ACP (Glock 21 upper)
.400 COR-BON

also there are some obscure wildcat calibers out there too