"Federal firearms regulation has been a subject of continuous interest for legislators. In recent Congresses, a range of proposals has been introduced, with some seeking to ease various federal firearms restrictions or facilitate reciprocity in state treatment of persons authorized to carry a firearm by another state. Other proposals have sought greater restrictions on the federal rules concerning the possession, transfer or sale of firearms,or the expansion of background checks for firearm purchases. These various approaches, in turn, prompt debate about not only their pros and cons but also their legalities, as Congress's ability to legislate on such matters must comport with the Second Amendment and other constitutional constraints."
CRS In Focus, IF11038
Congressional Research Service: https://crsreports.congress.gov/