The 5.56 Nato calibre is a semi-automatic that comes in both matte black and pink camouflage. You can use it for hunting pigs and coyote or, naturally, have one in the house just in case. Asked if it wouldn’t make more sense to call the police, Patrick Kisgen explains that by the time the police arrived you could be dead. “If someone broke into my house I’d want to get my gun and stand between them and my kids.” At a nearby stall a young woman hands out stickers announcing Ambush. “Wear that sticker and twice a day every day we’ll be giving out free firearms to someone who’s wearing it. You might be lucky,” she says.

The cavernous exhibition hall at the National Rifle Association convention hosts a veritable arsenal (none of them are loaded) of lethal weaponry – a supermarket of deadly Glocks, rifles, semi-automatics, Smith and Wessons, bullets and Brownings where people browse and try the killing machine for size. Some are raunchy. One huge poster shows a woman in a bra pointing a pistol towards the sky, and another of Jessica wearing a .22 LR and not much else with an invitation to get a signed poster.

George Zimmerman is behind bars. Six weeks after he shot Trayvon Martin, the state of Florida has been pressured, from above and below, to at least contemplate the notion that a man who killed an unarmed child might have a case to answer. He has now been charged with second-degree murder.

What follows from here has the potential to be every bit as divisive as the OJ Simpson trial and every bit as inflammatory as the Rodney King case – only this time there’s a black president in an election year. Blacks and whites already understand this case differently. A recent Newsweek poll showed that 80% of black Americans thought Martin’s death was racially motivated and 78% thought Obama’s comments about the shooting were appropriate. The figure for whites was 35% and 28% respectively. In the caffeinated, disaggregated world of cable news and blogs, where people feel entitled to their own facts, the details that emerge will only deepen these fissures.

In 1955 Mamie Till sent her 14-year-old son, Emmett, from Chicago to rural Mississippi to spend his summer holiday with family. As she packed him off she gave him some advice about how a black youth should conduct himself in the pre-civil rights south. “If you have to get on your knees and bow when a white person goes past,” she told him. ”Do it willingly.”

While in the small town of Money, in the delta region, he either said “Bye, baby” or wolf-whistled at a white woman in a grocery store. Three days later his body was fished out of the Tallahatchie river with a bullet in his skull, an eye gouged out and his forehead crushed on one side.