Glock interchangeability

[Tinman357]

I'm asking 'cuz I don't know. Can you change a G20 to a G21 with just an upper change?

IOW, can I convert my 10mm to fire .45acp I know my G22 will fire. 357sig .40s&w and 9mm with a barrel and mag change.

Getting the G21 upper and mags arent an issue. Will it work?

 

[Inebriated]

You can switch uppers.

 

[G21NE]

Yep, same frame size.

 

[Tinman357]

Excellent! Thanks.

 

[psyopspec]

Are the magazines the same too? I was under the impression that a 10mm cartridge shares the same case diameter (but shorter length) as a .40 SW whereas a .45 ACP is, well, a .45.

 

[Havok7416]

Are the magazines the same too? I was under the impression that a 10mm cartridge shares the same case diameter (but shorter length) as a .40 SW whereas a .45 ACP is, well, a .45.

10mm is 10x25mm and .40 S&W is 10x22mm. The .40 is nothing but a shortened 10mm (the 10mm was invented first and the .40 came along later).

 

[psyopspec]

10mm is 10x25mm and .40 S&W is 10x22mm. The .40 is nothing but a shortened 10mm (the 10mm was invented first and the .40 came along later).

Thanks. Follow-up: would a 10mm magazine function with .45 ammo if one were to just swap the slides on their Glock 20 to a Glock 21 upper? Or with the larger .45 cartridges, would they lie too low at the top of the magazine for the slide to effectively move them into the chamber?

 

[Havok7416]

10mm has a smaller diameter than .45 so the feed lips on the magazine would prevent .45 rounds from feeding into the magazine. Bending the feed lips open would cause 10mm rounds to not stay in the magazine (don't do that).

 

[psyopspec]

Thanks. So it looks like the answer to the OPs question is that you can change slides between the Glock 20 and 21 no problem, but would need the corresponding magazine to actually use the gun.

 

[Skribs]

Why stop at .45?

http://www.guncrafterindustries.com/sneakpreview.shtml

A visual aid to highlight the question for the OP

 

[powder]

The more affordable route: start with the G21, and just get a Storm Lake 10mm conversion barrel.

 

[eldon519]

Is the ejector the same between the 20 and 21? I have no idea myself, but I know on the 9mm vs. .40/357 SIG guns, the 9mm ejector bends inward because the 9mm case is smaller. Not sure if the 10mm/.45 situation would be similar.

 

[G21NE]

Is the ejector the same between the 20 and 21? I have no idea myself, but I know on the 9mm vs. .40/357 SIG guns, the 9mm ejector bends inward because the 9mm case is smaller. Not sure if the 10mm/.45 situation would be similar.

Oh yeah, forgot about that, you may need to change ejectors and/or trigger group housing. The 10MM being a smaller diameter case could have the effect of the ejector missing the case altogether, or barely hitting it and causing problems.

If it were the other way around, converting 10MM to 45ACP, it could cause an unintended discharge if the 10 mm ejector contacts the 45 primer when ejecting a loaded round. OR it may not chamber a round in the first place.

 

[hentown]

Same, exact lowers. Same ejectors, accordingly. Different extractors, making for the 10mm conversion barrels pretty "iffy", as a 10mm extractor won't work in a .45ACP slide.

 

[MassMan]

Changing from 40 S&W to 357 Sig requires a barrel change but the same mags will work.