...Q: Is it legal to assemble a firearm from commercially available parts kits that can be purchased via internet or shotgun news?
For your information, per provisions of the Gun Control Act (GCA) of 1968, 18 U.S.C. Chapter 44, an unlicensed individual may make a “firearm” as defined in the GCA for his own personal use, but not for sale or distribution.
The GCA, 18 U.S.C. § 921(a)(3), defines the term “firearm” to include the following:
… (A) any weapon (including a starter gun) which will or is designed to or may be readily converted to expel a projectile by the action of an explosive: (B) the frame or receiver of any such weapon; (C) any firearm muffler or silencer; or (D) any destructive device. Such term does not include an antique firearm.