text: The gun method has also been applied for nuclear artillery shells, since the simpler design can be more easily engineered to withstand the rapid acceleration and g-forces imparted by an artillery gun, and since the smaller diameter of the gun-type design can be relatively easily fitted to projectiles that can be fired from existing artillery.
  A US gun-type nuclear artillery weapon, the W9, was tested on May 25, 1953, at the Nevada Test Site. Fired as part of Operation Upshot–Knothole and codenamed Shot GRABLE, a 280 mm shell was fired 10,000 m and detonated 160 m above the ground with an estimated yield of 15 kilotons. This is approximately the same yield as Little Boy, although the W9 had less than 1/10 of Little Boy's weight (365 kg vs. 4,000 kg, or 805 lbs vs. 8,819 lbs). The shell was 1,384 mm long.
  This was the only nuclear artillery shell ever actually fired (from an artillery gun) in the US test program. It was fired from a specially built artillery piece, nicknamed Atomic Annie.  Eighty shells were produced from 1952 to 1953.  It was retired in 1957.
  The W19 was also a 280 mm gun-type nuclear shell, a longer version of the W-9. Eighty warheads were produced and the system was retired in 1963.
  The W33 was a smaller, 8 inch (203 mm) gun-type nuclear artillery shell, which was produced starting in 1957 and in service until 1992. Two were test fired (detonated, not fired from an artillery gun), one hung under a balloon in the open air, and one in a tunnel.
  Later versions were based on the implosion design.