Actually, this poses some interesting statutory issues even beyond the constitutional ones. A collection of parts that can be turned into a machine gun in less than eight hours using common machining equipment is legally considered to be a "machine gun". This raises some interesting questions as to when a "machine gun" is considered to be created (epsecially since by that definition a Volvo could be considered a machine gun).
Of course, the BATF doesn't care what's legal or not--just what they mildly dislike or severely dislike.
Under this definition everyone is a murderer. The Bureau of Alcohol Tobacco Firearms are just a bunch of bully thugs.