The third was recovered and inspected, allowing the discovery of a flaw in the contact firing mechanism that had plagued the Mark 14 torpedo for 18 months.

She made two attacks on Japanese convoys; although handicapped by malfunctioning torpedoes, she managed to damage a passenger freighter and a cargo ship.

During this patrol Muskallunge scored hits on a tanker and two freighters, sinking one of the Noroto Maru class, before returning to Pearl Harbor 21 January 1944.

In June she joined eight other submarines in an operation designed to intercept any enemy forces approaching the Marianas which the Navy was invading.

Muskallunge recommissioned 31 August 1956 prior to transfer to Brazil; decommissioned 18 January 1957, and the same day was loaned under the Military Assistance Program.

She served the Brazilian Navy as Humaitá (S14) until returned to the United States in March 1968 and sunk as a target off Long Island, NY on 9 July 1968.

The hull was found to have been severed near the forward engine room with the bow and stern falling to the sea floor separately.