Osmakac, 27, of Pinellas Park, was charged with possessing an unregistered automatic weapon and attempting to use a weapon of mass destruction. The jury found him guilty of both charges.
Osmakac, a naturalized citizen born in Kosovo, faces life in prison.
Osmakac was arrested Jan. 7, 2012, in the culmination of an FBI sting in which an undercover agent, posing as an arms dealer, provided him with inert explosives and non-working guns. Osmakac was arrested as he tried to pull away from a Days Inn parking lot with what he thought was a car bomb in his trunk.