Federal agents are trying to determine why a man pulled over for speeding in Tennessee was carrying a cache of weapons including two submachine guns and 900 rounds of ammunition. Deputies found Scott Edmisten, 43, of Johnson City, carrying a .357-caliber Magnum, a loaded .45-caliber semi-automatic, a .223-caliber fully automatic assault rifle, a .308-caliber fully automatic assault rifle, more than 900 rounds of ammunition, and survival equipment, Washington County Sheriff Ed Graybeal said.