Glock 38 slide width-1.3 inches
Glock 21 slide width-1.34 inches
Glock 23/22 gen 5 slide width 1.34 inches
My gen5 22 slide is the same width as my Glock 21
As an aside my gen5 Glock 22 seems to be much more shoot able than my gen 4 and will run with a WML on it.