SPRINGFIELD - When federal agents converged on Michael Paulus in Celina, Ohio, in 2004, he was chagrined, to say the least. The admitted air rifle enthusiast told an agent from the Bureau of Alcohol, Tobacco, Firearms and Explosives he was shocked to learn four unregistered silencers he owned were illegal, according to testimony yesterday in an ongoing federal firearms trial. Paulus was never charged in the investigation with roots in Western Massachusetts. "My impression of Michael Paulus is he is an upstanding citizen who had no idea he was breaking the law," ATF agent Larry K. Ward Jr. told jurors...