BOSTON — A Lowell man federal authorities say sold more than a dozen firearms illegally has been sentenced to almost five years in prison.Julio Gomez was sentenced to four years and nine months behind bars and three years of probation this week in U.S. District Court in Boston.The 30-year-old Gomez pleaded guilty in January to being a felon in possession of a firearm.Gomez was arrested last May 2, after investigators determined he was trafficking guns.