Federal laws regulating firearms traffic into, from and within the United States are the Gun Control Act of 1968 (GCA), 18 U.S.C. Chapter 44, the National Firearms Act (NFA), 26 U.S.C. Chapter 53, and the Arms Export Control Act (AECA), 22 U.S.C. 2778. Authority to administer and enforce these laws rests with the Secretary of the Treasury. The Secretary has delegated responsibility to enforce the GCA, the NFA, and the importation provisions of the AECA to the Bureau of Alcohol, Tobacco and Firearms (ATF). The authority to enforce the exportation provisions of the AECA is delegated to the United States Customs Service (USCS).
The GCA was enacted for the purpose of keeping firearms out of the hands of those not legally entitled to possess them because of age, criminal background, or incompetence. The GCA was also designed to make State firearms laws more effective by channeling interstate commerce in firearms through federally licensed businesses and generally confining firearms transactions by nonlicensees to their States of residence.
The NFA regulates certain classes of firearms, such as machineguns, short-barrel rifles, short-barrel shotguns, silencers, and destructive devices. The NFA requires that these weapons be registered by their makers, manufacturers, and importers and imposes taxes on transactions in such weapons.
The Arms Export Control Act (AECA), 22 U.S.C. 2778, gives the President the authority to control imports and exports of “defense articles,” including firearms and ammunition, in furtherance of world peace and the security and foreign policy of the United States. The AECA requires permits and licenses to import and export such articles. Imports to and exports from certain “proscribed countries” are prohibited. The Department of the Treasury administers the import controls of the AECA and has delegated this authority to ATF. The State Department and the Customs Service administer and enforce the export controls of the AECA.
Source: U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives