"Congress has debated the efficacy and constitutionality of federal regulation of firearms and ammunition, with strong advocates arguing for and against greater gun control. During the 112th Congress, several mass-casualty shootings punctuated public discourse on gun control. In a January 8, 2011, Tucson, AZ, shooting, 6 people were killed and 14 wounded, including Representative Gabrielle Giffords, who was grievously wounded. In a July 20, 2012, Aurora, CO, theater shooting, 12 people were killed and 58 wounded. In an August 5, 2012, Milwaukee, WI, Sikh temple shooting, 6 people were killed and three wounded. Several Members of Congress called for reconsideration of an expired ban on high capacity ammunition feeding devices (H.R. [House Resolution] 308 and S. 32), strengthening provisions designed to encourage states to make firearms-related disqualifying records more accessible to federal authorities (S. 436/H.R.1781), and tightening regulation of interstate ammunition transfers (S. 3458/H.R. 6241). [...] This report also includes discussion of other salient and recurring gun control issues that have generated past or current congressional interest. Those issues include (1) screening firearms background check applicants against terrorist watch lists, (2) combating gun trafficking and straw purchases, (3) reforming the regulation of federally licensed gun dealers, (4) requiring background checks for private firearms transfers at gun shows, (5) more-strictly regulating certain firearms previously defined in statute as 'semiautomatic assault weapons,' and (6) banning or requiring the registration of certain long-range .50 caliber rifles, which are commonly referred to as 'sniper' rifles. To set these and other emerging issues in context, this report provides basic firearms-related statistics, an overview of federal firearms law, and a summary of legislative action in the 111th and 112th Congresses."
CRS Report for Congress, RL32842