The National Rifle Association has announced it is pulling its 2007 national convention out of Columbus, Ohio because of the city’s ban on assault weapons. The City Council passed a ban July 12 outlawing the sale or possession of semiautomatic rifles with pistol grips and detachable magazines. The gun owners’ organization had planned to hold its annual three-day event, expected to draw as many as 60,000 people, at the Greater Columbus Convention Center.