A Dorchester man who served three years in prison on gun and drug charges is back behind bars after being caught with a second unregistered firearm and more than two dozen retail-ready bags of crack cocaine, Suffolk County District Attorney Daniel F. Conley said.

SHAWN J. YOUNG (D.O.B. 12/26/80) was arraigned yesterday in Dorchester District Court on charges of trafficking in cocaine between 14 and 27 grams, violating the state’s drug laws within 1000’ of the John Marshall Elementary School, unlawful possession of a firearm, and unlawful possession of ammunition.

In light of 2006 Suffolk Superior Court convictions for unlawful firearm possession and possession with intent to distribute a Class B substance, Young is charged as a Level I armed career criminal. Judge Michael Coyne set his bail at $100,000.

Assistant District Attorney Brendan Cox told Coyne that members of the District 11 Boston Police Drug Control Unit hit Young’s Topliff Street apartment on a search warrant at about 11:00 Tuesday morning, just as Young was getting out of bed.

While executing that warrant, police found in Young’s dresser a .45 caliber Taurus Millennium semiautomatic handgun loaded with 10 rounds of ammunition. They also recovered a bag of crack cocaine, a scale, and plastic baggies on a desk near his bed. Inside a pair of shorts on Young’s floor, police also found 25 plastic bags of crack cocaine individually packaged for retail sale.

Police also seized from the scene a total of $2042 and three cellular phones.

Young was represented yesterday by attorney Stephanie Soriano. He will return to court on Sept. 2.