Originally Posted by Esox357
A Glock 20 can shoot 10mm, 40 Sw, and swap to 45 acp from my understanding.


Would require a complete G21 or G41 upper to switch the G20 to .45ACP. Shared frame dimensions, different slide bore between G20 and G21/G41.
Vendors make barrels for .40S&W, 9mm and .357SIG for drop in.
A factory G20 barrel will shoot .40S&W. Some will get bent out of shape with that subject.