WASHINGTON — The Obama administration on Monday approved a new regulation requiring firearms dealers along the Southwest border to report multiple sales of certain semiautomatic rifles, a rule intended to make it harder for Mexican drug cartels to obtain and smuggle weapons from the United States. Under the rule, dealers in Arizona, California, New Mexico and Texas will be required to inform the Bureau of Alcohol, Tobacco, Firearms and Explosives if someone buys —... (GunPolicy.org)