[tahunua001]

I think you are being just a little bit too imaginative here. the glock 20 is by no means the AR15 of the pistol world. the 10mm is essentially an enlongated 40 S&W so there would really be no difficulty swapping a 40 barrel for the conversion and using the same magazine. 357 sig is the same story, a 40 cal casing necked down to 9mm-ish diameter. I have personally seen a person feed a box of 9mm through a glock 22 accidentally. everything fired and no problems other than every single casing ruptured and accuracy was pathetic. given that knowledge, I see no reason why a 9mm conversion would not work.

I have personally picked up casings in my driveway for 380s... I don't own a 380 meaning that those were fed through my 9mms so in theory, you could drop a 380 barrel in the glock and still use the factory 10mm mags.

however that is where all easy swaps are exhausted. there are dozens of conversions to convert to 22lr but as I understand it you need to replace the entire slide assembly and the 10mm mags will definitely not work so you also need 22 magazines.

I think those 5 calibers are about all you'll ever get.