While it may seem hard to believe now, the U.S. military had tried during World War II to develop a gun that could fire a nuclear bomb.
The Manhattan Project
The gun capable of firing a nuclear bomb was officially known as the "Mark 2." Although most of the scientists and engineers who worked on its development called it by the code name "Thin Man." The unusual gun was put into the design phase as part of the infamous "Manhattan Project," the U.S.-led initiative that developed the first atomic bomb during World War II, and built the bombs that were dropped on Hiroshima and Nagasaki. J. Robert Oppenheimer, the physicist who led the Manhattan Project, was intimately involved in the development of the "Thin Man" gun.
The intention of the gun was to be a delivery system for a nuclear bomb. The gun had been designed to be two feet wide and 18 feet long with a weight of 7,500 pounds. It was hoped that the gun could fire a "plutonium bullet" across great distances at more than 3,000 feet per second. For a time in 1943, the "plutonium gun" as Mr. Oppenheimer called it, received the bulk of scientists’ attention who were involved in the Manhattan Project.
Despite the best efforts of Mr. Oppenheimer and his team, the Thin Man gun was eventually abandoned in 1944 in favour of a more conventional bomb, or "plutonium implosion." In the end, the scientists working on the gun concluded that the risk of exposure to deadly radiation or plutonium was too great. As well, the test firing of prototypes of the gun found that it was unstable and unreliable. Modifications were made to try and make the bullets or bombs fired from the gun more aerodynamic but they were not successful.