Change a G21 to 10mm?

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Change a G21 to 10mm?

Post by Lead ball » Thu Jul 14, 2016 12:39 pm

Can you put a 10mm barrel in a G 21 thanks

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Re: Change a G21 to 10mm?

Post by Masonryman » Thu Jul 14, 2016 12:59 pm

Lead ball wrote:Can you put a 10mm barrel in a G 21 thanks
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Re: Change a G21 to 10mm?

Post by RLHas » Thu Jul 14, 2016 1:06 pm

You can actually!
I in no way advocate doing so but Bar-sto, EFK and Storm Lake all make a G21 to G20 conversion barrel.
You change the barrel and mags and you are ready for the range.
Not sure if the extractor would need changed or not.
I received a Bar-sto barrel once in trade. I just fitted it to my G20
Was an amazingly accurate barrel

https://www.efkfiredragon.com/glock-21- ... sion1.html
Last edited by RLHas on Thu Jul 14, 2016 1:14 pm, edited 1 time in total.
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Re: Change a G21 to 10mm?

Post by ron » Thu Jul 14, 2016 1:14 pm

You can't put a standard 10mm barrel in G21 but they mak3e conversion barrels. The Glock doc,(and Rick correct me if I'm wrong) doesn't like converting a cartridge with a smaller rim size to fire in a gun with a breech face that is made for a larger case size because potentially the extractor claw might not have enough purchase.

I don't think this is critical because Glocks have very good extractors which grip a large portion of the rim and they're spring loaded. My KKM conversion barrel in my Glock 23 works very well and the difference in case rim size is slightly greater between a 9 and a 40 than it is between a 10 and a 45.
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Re: Change a G21 to 10mm?

Post by Flawlessfoose » Thu Jul 14, 2016 8:17 pm

I believe firmly that the 45 to 10mm conversion barrel is a waist of money because there is more than likley going to be reliability issues. If you want to do it right you should get a complete G20 slide assembly. Yes it does cost more, but you essentially have guns in one.
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Re: Change a G21 to 10mm?

Post by ron » Thu Jul 14, 2016 9:28 pm

Flawlessfoose wrote:I believe firmly that the 45 to 10mm conversion barrel is a waist of money because there is more than likley going to be reliability issues. If you want to do it right you should get a complete G20 slide assembly. Yes it does cost more, but you essentially have guns in one.
I'm beginning to agree with you. From what I've been able to find out, the G21 extractor needs to be modified to be able to grip all the way into the smaller 10mm case extractor groove and I don't think that's a job for the home handyman with a dremel tool. As I said before it doesn't seem to be an issue with the 40 to 9mm conversion. The other thing about that KKM conversion barrel was that the chamber is slightly offset to put the case head closer to the extractor. I took it to Rick to examine and he found that the amount of offset is very slight, what might best be described as fractional.

The 9mm rim is 0.380 and the depth of the extractor groove is at 0.330. the 40/10mm rim is 0.427 and I couldn't find a dimension for the depth of the groove. The 45 ACP rim is 0.480 and the depth of the groove is 0.400 Contrary to what I said earlier the difference between the 10mm and the 45 is actually slightly greater than the difference between the 40 and the 9. ( 40 to 9mm= .53, 10mm to 45= .47)


So if the G21 extractor needs to be modified to work with 10mm conversion barrel, the question is, will it still work as well with the 45 cases after it's been modified?

But where do you get complete Glock "Uppers" (slides with all necessary parts installed) and what do they cost? I have the feeling that they cost about 2/3rds of what the entire gun costs. And I don't think you can buy Glock factory slides and all the aftermarket ones are Butt-ugly, with some worse than others. (See illustration)

Since I can't afford another gun right now or even two-thirds of another gun, I think I'll just stick with my G20 for shooting 10mm and my 1911 for shooting 45 ACP. 8-)

Update: I just found out that Glockmeister occasionally has factory Glocks slides available for about $360.00 Here's what it says on their website:

"GLOCK factory slides and receivers are items we receive on an infrequent basis. As they are high demand items, frequent back-orders and significant wait times may occur. Upon arrival we dedicate these slides and receivers starting with the oldest order, working our way to the newest order placed. Wait times vary by demand and by the number of the items received."
Last edited by ron on Wed Oct 05, 2016 7:34 pm, edited 1 time in total.
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Re: Change a G21 to 10mm?

Post by rem300ultra » Wed Oct 05, 2016 9:05 am

Doing this conversion is no problem at all. I did it to mine. However, I bought basically a complete package from kkm. I bought their barrel, new extractor and spring. The extractor is set up to function with .45 and 10mm. It functions flawlessly. It is extremely accurate with that barrel. The only issue I have is I need a little stiffer spring when I shoot buffalo bore or underwood ammunition in it, but that is to be expected.

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Re: Change a G21 to 10mm?

Post by ron » Wed Oct 05, 2016 7:32 pm

rem300ultra wrote:Doing this conversion is no problem at all. I did it to mine. However, I bought basically a complete package from kkm. I bought their barrel, new extractor and spring. The extractor is set up to function with .45 and 10mm. It functions flawlessly. It is extremely accurate with that barrel. The only issue I have is I need a little stiffer spring when I shoot buffalo bore or underwood ammunition in it, but that is to be expected.
+1!

Thanks for this information. I have a KKM 9mm conversion barrel for my Glock 23 and it works fine with the standard Glock G23 factory extractor. But I carry the gun as either a 40 or a 357 Sig and only use the 9mm barrel for plinking, but I've fired a lot of 9mm ammo through it and never had any FTF's.

I also have a Glock 20 Gen 3 SF and have fired some Buffalo bore, Double Tap, and underwood ammo through it and never had a problem using the standard weight spring although I did replace the factory spring with a Lone wolf unit with the stainless guide rod.
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