Colt UMAREX AR-15 type M4 Carbine M4 A3 .22 lr

[liqrdrms]

does any one know if the Colt UMAREX AR-15 type M4 Carbine M4 A3 .22 lr upper be replaced with a 5.56 upper?

 

[SilentScream]

No, the fire control system is totally different, as well as the lower being designed to NOT accept a 5.56/.223 upper.