George Zimmerman is hardly the only American who owns a gun, and gun sales increase with every high profile shooting. "Stand Your Ground" laws in Florida and 24 other states protect more killers who use guns with increasingly broad definitions of "self-defense." But there's a paradox. The share of American households with guns has dropped like a stone, declining from 50 percent in the 1970's to 34 percent in 2012. Is there a chance that gun control could make a political comeback?