Retired Rear Adm. Frederic Stanton Withington, 82, a scholarly weapons expert whose intellect and pragmatism helped steer the Navy into the age of missiles and atomic power, died Dec. 22 at Georgetown University Hospital. He had cancer.

A line officer from the old battleship school, Adm. Withington served during World War II as gunnery officer and and executive officer of the USS Indiana in the South Pacific and later commanded the USS Mississippi and the cruiser USS Manchester.

He probably made the greatest impact of his 38-year Navy career, however, from 1954 to 1958 as chief of the Bureau of Ordnance of a postwar Navy in transition.

During his tour of duty at the bureau, the Navy developed the Talos, Terrier and Sidewinder missiles, pushed torpedo science into the modern age and took major development steps toward the submarine-launched Polaris missile, an important element in the nation's nuclear deterrent ever since.

In a 1958 "valedictory" speech of characteristic candor, Adm. Withington said any such achievements must be balanced by the failure of arms officials, including himself, to halt the spiraling cost of modern weapons.

Instead of blaming inflation or increasing technical complexity for the budget-straining price of defense, he said costs could and should be cut by improved conceptual "ingenuity and sound thinking," "cost-conscious" engineering and a reduction in the number of missile programs that reach the "hardware" stage.

Adm. Withington was born in Rutherford, N.J. He was assigned to the Bureau of Ordnance upon graduation from the U.S. Naval Academy in 1923. In the years that followed, he alternated sea duty aboard battleships and cruisers with shore assignments in the ordnance bureau, where Pearl Harbor found him organizing weapons production. In April, 1942, he joined the Indiana, then the newest battleship of the fleet.

After the war, Adm. Withington directed the Naval Ordnance Laboratory in White Oak, Md. In 1950, he was chosen to direct the Navy's Atomic Energy Office during work on the first nuclear submarine.

He also was a graduate of the National War College. After promotion to flag rank, he commanded Amphibious Group III in the northern Pacific. He retired in 1961 as commander of U.S. Naval Forces in Japan.

His decorations included two Legions of Merit.

Adm. Withington, who lived in Washington, was recalled to active duty four times in succeeding years to serve on Naval advisory boards, including those pursuing development of the recently operational and highly sophisticated Aegis shipboard missile system.

Survivors include his wife, the former Louise Fifield Gleason, of Washington; a son, Frederic G., of Concord, Mass.; a daughter, Joyslin W. Bushman of Dover, Mass.; a brother, Edwin, of Seymour, Conn.; a sister, Neale Reichle of Fayetteville, N.C.; six grandchildren, and a great-grandson.