View Full Version : Converting a Glock 20

10-06-2011, 4:43 PM
I recently purchased a glock 20. I was told that I could convert it by simply putting in a glock 22 barrel (40 s&w) and using glock 22 magazine. Is this true or do I need to do some other modifications. Sorry if this is well known answer but I am new to the wonderful world of glocks.

10-06-2011, 4:47 PM
It depends on if the .40 S&W mags are have the same external dimensions of the 10mm mags which I doubt they would.

2nd Shot
10-06-2011, 4:50 PM

You can put the barrel and mags from the Glock 21, in .45 ACP in it, as they share the same frame and slide dimensions. The Glock 20 slide is heavier than the .45 so you may or may not need to change the spring or use heavier/hotter loads to get good function - I've never tried it, so I don't know.

The Glock 22 (.40) is a completely different frame and slide size and will not work, although you could possibly find a "conversion barrel" that has the same dimensions as the 10mm/.45 barrel on the outside, and a .40 chamber and bore. You probably need to use 10mm magazines, since .40 will fit, but be shorter than normal.

10-06-2011, 4:53 PM
You would continue to use your G20 mags as the G20/21 are large frame Glocks and the G22 is a small frame Glock.

I believe the accepted route for a barrel is one of the Lone Wolf drop ins that go from 10mm to 40 S&W. You'd need to go to a Glock forum for the final word but I'm pretty sure the above info is correct.

Take care,

10-06-2011, 5:04 PM
You can convert it to 40 s&w or 357 sig (or 9x25 dillon or whatever) with a conversion barrel, and keep using the same mags as before. You cannot convert it to 45 acp, because the breechface is to small to hold the cartridge.

10-06-2011, 5:54 PM
You have to use your G20 mags & a 10mm-40S&W conversion barrel (Lone Wolf, KKM, Storm Lake etc). The 40's function just fine in an unmodified G20 mag.

10-06-2011, 9:25 PM
Here’s what I think you want, it’s lonewolf conversion barrel, you just swap it out and use your 20 mags.


10-06-2011, 9:33 PM
In before Bob!

All you need is the conversion barrel. You can use the same extractor, ejector, magazines, and all. Reliability has been 100% on mine, but I still would never use a conversion barrel like that for defensive purposes. I recommend using the caliber the gun was chambered in from the factory, unless of course you changed all the appropriate parts, which is impossible on the G20 to go to a G22.

10-06-2011, 9:46 PM
Thanks guys for all the input. I wanted to do the conversion just for training purposes. 10mm ammo is a little pricey and 40 is a lot more cost efficient

10-06-2011, 9:55 PM
Thanks guys for all the input. I wanted to do the conversion just for training purposes. 10mm ammo is a little pricey and 40 is a lot more cost efficient

And that's why I own a G17 along with my G20. 9mm ammo is far cheaper than anything else.

The .40 and 10 do not shoot the same. Felt recoil in the 10mm is more imo, with the .40 being far snappier. But, just a barrel swap and you can shoot 40's all day long.


10-07-2011, 6:20 AM
I just did this with a Lone Wolf 10mm-40 S&W conversion barrel. You use the same 10mm mags and recoil spring. I love the larger frame, less recoil than even a regular Glock .40 due to more mass and yes, cheaper to shoot as well. The barrel I got is blind marked.