<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> The Gun Control Act of 1968 (GCA or GCA68) is a U.S. federal law that regulates the firearms industry and firearms owners . It primarily focuses on regulating interstate commerce in firearms by generally prohibiting interstate firearms transfers except among licensed manufacturers, dealers and importers . </P> <P> The GCA was signed into law by President Lyndon B. Johnson on October 22, 1968, and is Title I of the U.S. federal firearms laws . The National Firearms Act of 1934 (NFA) is Title II . Both GCA and NFA are enforced by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). </P>

When did they start putting serial numbers on guns