Although about the M4 debate: There was a skirmish in court between Colt and Bushmaster a few years back, Colt being upset at Bushmaster for making reference to one of their models being an M4.
Court ruled out that since the term had become so common and was way out of patent refference, the term M4 can be used to designate any AR-15 type rifle that comes close to the original idea. It's become more of a general reference name.
Bottom line is, these babies are probably as close as what you'll find to a ''real'' M4.