Agents in S.C. refer more cases to U.S. attorney's office. Federal agents are cracking down on gun offenders in South Carolina, sending hundreds of cases to federal prosecutors each year -- up from a few dozen five years ago. And those cases -- handled by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives -- are resulting in convictions: 116 in 2002, compared with half that in 1998. "We are targeting the worst of the worst," said Strom Thurmond Jr., the U.S. attorney for South Carolina. "When someone with multiple violent convictions is sentenced to a substantial amount of time...