As the sun sets over rural North Carolina, Dwayne Dixon peers through black-rimmed glasses down the barrel of an AK-47. Abandoned cars and rusted-out trailers dot the overgrown property; cows graze in a nearby paddock under the gathering shadow of pine-clad hills. Softly-spoken and slight of build, Mr Dixon is a vegan who spends his days lecturing in anthropology at a local university. Today he's preparing for the moment he may raise a deadly weapon on the streets of a US city. "Guns are a tool," he says between bursts of crackling gunfire. "You'd rather have it and not need...