The Obama administration took a concrete step toward curbing the flow of semiautomatic weapons to Mexico last week when it adopted a new regulation mandating the reporting of multiple sales of long guns to federal authorities. Under the regulation, some 8,500 licensed gun shops in Arizona, California, New Mexico and Texas will be required to inform the Bureau of Alcohol, Tobacco, Firearms and Explosives when a customer buys more than one semiautomatic that is .22... (GunPolicy.org)