No, except that frames or receivers of firearms are “firearms” as defined in the law and subject to the same controls as complete firearms. Silencer parts are also firearms under the GCA, as well as under the National Firearms Act (NFA). Certain machine gun parts, such as conversion parts or kits, are also subject to the NFA.
[18 U.S.C. 921(a)(3) and (24), 26 U.S.C. 5845, 27 CFR 478.11 and 479.11]