Last October in Laredo, a K-9 caught the scent of gunpowder. Following the dog’s lead, federal agents entered a trailer and pulled down a false wall of plywood. There lay hundreds of deadly weapons, stacked from floor to ceiling and bound in plastic wrap. Between two trailers, officers counted more than 300 pistols and rifles, plus ammunition, all headed toward the Mexican border, as the Laredo Morning Times reported. Such discoveries aren’t rare.