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Old 07-28-2011, 07:43   #1
arushus
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Will .40cal ammo run in a stock G20?

I realize this is probably a stupid question but I just have to ask because there's a few reasons it makes sense to me that .40 ammo would run in a stock G20. Arent they the exact same bullet, just shorter brass and less powder? I know it would probably be best to just buy a 10mm to .40 conversion barrel, but really, would there be a difference in the barrels since both bullets are the exact same size? Well, almost, I have read where some 10mm ammo is actually .401", while .40cal is .400"....thanks in advance for sharing your knowledge!
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Old 07-28-2011, 08:18   #2
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The big problem is the 10MM round is longer than the .40 round. Being rimless, both rounds 'seat' on the forward part of the cartridge edge.
(case mouth) against a machined rim inside the barrel.

Push a .40 cartridge into a 10MM barrel and you will notice it goes inside the chamber about a quarter inch beyond flush, before the case mouth hits the machined rim. Sure it will feed into the chamber but you would have to rely on the extractor to hold the case flush with the end of the barrel; then the bullet would have to 'jump' the gap, eventually wearing out that machined rim.

Why ruin a good 10MM barrel?...maybe in an emergency you could run some rounds thru, but that would depend on the extractor 'grabbing' the rim perfectly every time, holding the cartridge while the firing pin did it's job.

Spend the money and get a .40 barrel for your Glock.

JMO

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Old 07-28-2011, 08:21   #3
rjkobbeman
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You need a conversion barrel.

The reason is not because of diameter differences (the .40 and 10mm are the EXACT same projectile and case diameter), but due to the .40 being a shorter case. If you drop a .40 in a 10mm barrel, the .40 will drop down too far into the barrel.

The chamber on the .40 barrel is not as deep as the chamber on a 10mm barrel.

Theoretically (sp?) the extractor would keep the cartridge in the proper location, however that is NOT what you want to rely on. Also, even if the extractor held the cartridge in the proper location, there will be a portion of the chamber in front of the projectile that is a larger diameter than the rest of the barrel. This could cause issues the moment the projectile leaves the case.

Shooting .40 S&W in a 10mm handgun is not a problem and is done all the time, however you must get a .40 conversion barrel to do it. No other changes are required.

I shoot .40 S&W out of my G20 all of the time. I also have a .357 Sig conversion barrel but have not used it yet.
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Old 07-28-2011, 09:01   #4
arushus
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thanks fellas, I knew it was a stupid question, I just didnt know why, haha. Your responses make perfect sense....thanks for clearing that up!
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Old 07-28-2011, 09:25   #5
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it will work... there are youtube videos of people doing it... I wouldn't do it unless it was an emergency for reasons already listed
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Old 07-28-2011, 09:50   #6
THE PUNISHER
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I can shot 40sw out of my G20 witha LW conv. barrel and factory spring.....22lbs spring not so good.
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Old 07-28-2011, 14:45   #7
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It'll work. I wouldn't recommend it though.

The extractor holds the brass against the breech face and it'll shoot no doubt.

If it were to get out from under the extractor or somehow the bullet didn't enter the barrel correctly there could be a problem.

Definately not for edc.
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Old 07-28-2011, 15:47   #8
_The_Shadow
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The safest way is with the conversion barrel which is properly head spaced for the 40S&W cartridge. This is the method I use in my 10mm pistols!

Using a standard 40S&W you are completely dependant on the extractor to hold the cartridge in proper position to be struck by the striker or firing pin. Sometimes they can be knocked off without being fired, this is rare.

There were some people who were loading their own 40S&W ammo, who loaded the bullets long, this aided to head space bullet on the trueing cone/rifling of the 10mm barrel. This provided a fairly positive head spacing...word of caution is if a bullet were to get stuck in the rifling and pull free from the cartridge.
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Old 07-28-2011, 17:36   #9
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In an emergency it works.
Best to have a conversion barrel.
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Old 07-28-2011, 20:00   #10
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Can a couple of BigMacs take care of hunger rather than a 24ounce steak dinner? Yes. And cheaper, too. But WHY?
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Old 07-28-2011, 20:35   #11
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This is a much cheaper (and safer) alternative to shoot 40 out of it compared to the cost of a new gun and/or medical bills......

http://www.lonewolfdist.com/Detail.a...OD=951&CAT=238
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Old 07-28-2011, 21:49   #12
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I once tried to put a .40 in my G20 with my right hand and my left hand kept slappin' the hell out of me every time I tried. I guess it just wasn't happening for me.
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Old 07-28-2011, 22:49   #13
arushus
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hahaha, everybody's a comedian....Im well aware of conversion barrels, thanks guys
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Old 08-03-2011, 18:16   #14
BruceO
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http://thegunzone.com/10v40.html


This is pretty much game, set, match although I do not agree with the author that it's ok to do in the case of the SA Omega w/ the double extractor's.
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Old 08-03-2011, 20:55   #15
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My G20SF will run 40 S&W with no problem. I tried it to see a couple of months ago. Used the G20 mags and had no problems.
I do not suggest you do it except maybe to test it!
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