LAWRENCE – A Lynn man was sentenced Friday to serve three and one-half to seven years in state prison for trying to rob a 52-year-old man with a BB gun on Union Street in 2009.Jeffrey Little, 49, formerly of 20 Park St., #30, Lynn, was found guilty last week by a Lawrence Superior Court jury of armed assault with intent to rob and assault with a dangerous weapon.Assistant District Attorney Greg A. Friedholm presented evidence during the trial that on Sept. 11, 2009, Little tried to rob the man near 269 Union St.Lynn police officers Gary Haggerty and Michael Kmiec were on routine patrol at about 11:15 p.m., when they came upon the incident as Little was putting a BB gun to the victim?s head and rummaging through his pockets.