This was the only artillery piece that ever fired nukes. It was at Ft. Sill the only time I saw it back in 1969.
http://en.wikipedia.org/wiki/Nuclear_artilleryThe first artillery test was on May 25, 1953 at the Nevada Test Site. Fired as part of Operation Upshot-Knothole and codenamed Shot GRABLE, a 280 mm (11 inch) shell with a gun-type fission warhead was fired 10,000 m (6.2 miles) and detonated 160 m (525 feet) above the ground with an estimated yield of 15 kilotons. This was the only nuclear artillery shell ever actually fired in the US test program. The shell was 1384 mm (4.5 feet) long and weighed 365 kg (805 lb); it was fired from a special artillery piece, nicknamed "Atomic Annie", built by the Artillery Test Unit of Fort Sill, Oklahoma