Gen4 21 to 10mm [Archive] - Glock Talk

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Quarter Tank
08-05-2012, 12:42
Okay so I want to make the plunge to 10mm and was trying to hold out and get a Gen4 20 but decided to transform my 21 to 10mm.

Question, will all aftermarket barrels, kkm, LW etc fit in a Gen4 without modification? Will my Gen4 rsa work with an aftermarket G20 barrel. Will I need a 10mm extractor?

Thanks in advance.


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alwaysshootin
08-05-2012, 13:12
From what I've heard/read, yes they will. If you are open to advice, take a look at what you will have tied up, monetarily speaking, in converting your 21. Make sure to add in the cost of a couple of mags, you know you'll need those! Then check what you can get into a used G20 for in your area. They usually come with at least two mags. You may just find it to be beneficial, to go with another firearm, to get you your G20.:cool:

larson1122
08-06-2012, 03:18
From what I've heard/read, yes they will. If you are open to advice, take a look at what you will have tied up, monetarily speaking, in converting your 21. Make sure to add in the cost of a couple of mags, you know you'll need those! Then check what you can get into a used G20 for in your area. They usually come with at least two mags. You may just find it to be beneficial, to go with another firearm, to get you your G20.:cool:

:goodpost:

As far as the extractor, you may need it and you may not. From what I understand some people have no problems using the stock 45 extractor with 10mm and others have needed to modify it in order for it to run reliably. I would try it out before doing anything with the extractor and see how it goes. I believe your stock RSA will be fine with 10mm as well.

I'm going to have to agree with the above advice and suggest looking into a used G20 or waiting a little while longer for the Gen 4 if that's what you really want. If you end up liking the 10mm (I'd be willing to bet you will love it), then I'm sure down the road you will want a dedicated gun in 10mm anyway. By the time you buy the conversion barrel, mags, etc. you are very close to the cost of a used G20, which can be found quite easily in good condition.

I have a Gen 4 21 and really enjoy it, but I picked up a G20SF recently and am glad that I don't have to mess around with conversion barrels and extractor modifications.

Good luck and enjoy the 10mm! :wavey:

Quarter Tank
08-06-2012, 04:57
I might go ahead and pick up a 10mm barrel regardless. I want to use a KKM barrel over stock even if and when I get my G20.

Thanks for the helpful advise. B

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humphreys19
08-07-2012, 10:24
You will not be able to use a .45 to 10mm conversion barrel ( what you need to convert your G21 ) in your future G20. The barrel hoods are different widths, due to the difference in breech face width between .45 and 10mm. This is the same reason you can't just drop a 20 barrel into a 21 to convert.

Tom

Yondering
08-07-2012, 19:06
This is the same reason you can't just drop a 20 barrel into a 21 to convert.

Tom

You can just drop a 20 barrel into a 21. It works great. The barrel hood is too narrow, but the sides of the barrel aligned in the slide perform the same task; no issues there.

humphreys19
08-07-2012, 22:23
Yondering,
That's news to me. I thought I was up on the 10mm conversion thing, and you tell me the 20 barrel will work in a 21? I thought the conversion barrel was needed. You have done this? How is reliability, feeding, ejection, etc.? The narrower barrel hood causes no problems? Do you need to change or modify the extractor?
It doesn't really matter much to me anymore, because I recently acquired a 20SF, but I am always curious about conversion possibilities.
Thanks, Tom

WeeWilly
08-07-2012, 23:13
Yondering,
That's news to me. I thought I was up on the 10mm conversion thing, and you tell me the 20 barrel will work in a 21? I thought the conversion barrel was needed. You have done this? How is reliability, feeding, ejection, etc.? The narrower barrel hood causes no problems? Do you need to change or modify the extractor?
It doesn't really matter much to me anymore, because I recently acquired a 20SF, but I am always curious about conversion possibilities.
Thanks, Tom

The barrel fits fine. There is a gap on both sides on the hood where it contacts the breech face where the wider 21 slides fills, but otherwise it fits fine. The extractor doesn't sit as far in, so I suppose you could have feed issues, although others here have reported no problems with the extractor. There is a mod for the 21 extractor that files the button that provides positioning that supposedly allows the 21 extractor to sit deeper without affecting reliability in 21 mode.

Another difference is slide weight. The 21 slide is lighter than the 20, so if you shoot real 10mm rounds, slide velocities will be higher, perhaps problematically as pressures go up.

I agree with others that say to get a dedicated gun, minimally, I probably get a complete 20 slide assembly, then you have factory/duty reliability on your hip.

Yondering
08-08-2012, 00:27
Yondering,
That's news to me. I thought I was up on the 10mm conversion thing, and you tell me the 20 barrel will work in a 21? I thought the conversion barrel was needed. You have done this? How is reliability, feeding, ejection, etc.? The narrower barrel hood causes no problems? Do you need to change or modify the extractor?
It doesn't really matter much to me anymore, because I recently acquired a 20SF, but I am always curious about conversion possibilities.
Thanks, Tom

I use a 10mm 6.6" Lone Wolf G20 barrel in my 21 slide with no other modifications. I have not had any issues with it, function is 100%. I do use a muzzle brake on it, because the lighter slide of the 21 is a significant difference. The inner sides of the slide locate the back end of the barrel, doing the same job as the barrel hood. Accuracy doesn't seem to be compromised with this setup.