i agree the .223,5.56, and 22lr are about the same bore size, but what about the chamber?
the kits have a bolt assembly that looks to have 22lr chamber built in, tippman barrels look to be chambered for 22lr.
here what i'm talking about,
from the cmmg kit link you post,
Tippman M4 22LR barrel
here is a screen shot from their barrel removal video, he tells at the 3:24 mark to about the extractor grove on the barrel.
video
AR barrel
now granted different mfg's make theirs in different ways, but it's a fact that your not going to force a .223 or 5.56 round into a 22lr chamber. well
you might if your very determined to.
edit on 15-4-2023 by BernnieJGato because: try to post better barrel images