If it is bent into the shape of an AK receiver and has more than 80% of the work completed then it is a firearm and must be shipped to, and transferred through an FFL. Not sure about the parts...best bet is to check BATFE web site to determine what is restricted under NFA.
"The whole of the Bill (of Rights) is a declaration of the right of the people at large or considered as individuals.... It establishes some rights of the individual as unalienable and which consequently, no majority has a right to deprive them of." (Albert Gallatin of the New York Historical Society, October 7, 1789)
"A free people ought not only to be armed and disciplined, but they should have sufficient arms and ammunition to maintain a status of independence from any who might attempt to abuse them, which would include their own government." - George Washington