One issue is a 22LR Barrel is shorter then a 223 barrel even if they were both 9”. This is due to the rifling going back into the reciever to meet the BCG on the 22LR kits (the chamber is further back into the receiver then on centerfire uppers). So my 11.5” 22LR barrel is the same as a 10” 223 Barrel for length past the receiver.
CMMG may measure differently, but this is true for Spikes and Walther/Umarex (they make the Colt M4 and HK416 22LR rifles).
Hope that makes sense.