Prior gun-type detonations were the Little Boy Mark-2 nuclear weapon Sandia 1967 History of Mk 4 bomb Document, Sandia Laboratories; Accessed Nov. 10, 2019 used on Hiroshima in World War II, and a test firing of the W9 11 inches nuclear artillery shell in test shot Upshot-Knothole Grable on May 25, 1953. [