On 1 February 1951, Bang was recommissioned at the U.S. Naval Submarine Base, New London, Lieutenant Commander Eugene A. Hemley in command, but spent only 15 months on active duty with the Atlantic Fleet before being decommissioned again on 15 May 1952 for conversion and modernization. Following work at the Portsmouth Naval Shipyard, Bang was recommissioned as a GUPPY IIA submarine, the first of her type to serve the U.S. Navy, on 4 October 1952, Lieutenant Commander Perry Hall in command. Although her outward appearance remained the same, Bang's internal arrangements were improved and incorporated impressive advances in ordnance and electronic gear.