Border gun shop owners sue over new requirement – Gun store owners in states along the U.S.-Mexico border sued the acting director of the federal agency that oversees firearms to halt a new requirement that they alert authorities if someone buys multiple high-powered rifles in a five-day span.  The requirement, which goes into effect Aug. 14, follows a controversial 2009 law enforcement operation in Arizona known as “Fast and Furious” that resulted in more than 2,000 high-powered weapons making their way to Mexico as authorities went after people directing gun buys on behalf of cartels.  The operation has been the subject of recent congressional hearings in which the Bureau of Alcohol, Tobacco, Firearms and Explosives acknowledged making mistakes.