I bought the Colt (mfg by Walther) M4 Carbine because I have four Grandchildren ranging in age from 5 to 16 to teach Firearms Safety, Maintenance and anything else they need to know. Using .223 would be cost prohibitive. When I am comfortable with their level of competence I have an M4 style AR for them to step up to. Not a lot of thought required. They look the same, work the same save for the (Bullet Button), have 10rd magazines. Makes perfect sense to me.