May 25, 1953; 280 mm Canon Fires Nuclear Weapon

This is the first test of a nuclear artillery shell (Grable for “gun“) - the 280 mm AFAP (artillery fired atomic projectile). The shot was an artillery delivered airburst. The shell travelled 11,000 yards before detonation which occurred 86 feet west, 137 feet south, and 24 feet above the designated burst point. The predicted yield was 14 kt. The Mk-9 280 mm ( inch) shell was 54.4 inches long, weighed 803 lb, and used oralloy as the fissile material. Air burst detonation was arranged by a time fuze. The Mk-9 was fired by an enormous 85 ton artillery piece. The gun had a muzzle velocity of 2060 ft/sec, and a range of up to 20 miles.