The 36-Inch Little David heavy mortar is the largest gun ever built, beating the German Dora and Karl. The reality is somewhat less spectacular: during World War II, the US often used phased out large caliber barrels to test bombs, using a small propelling charge to send them on a test target a few hundreds yards away. With the increasing sizes of the bombs, 9.2-Inch or 12-Inch barrels became insufficient, hence the building of this 914mm barrel.
Until October of 1944, it was no weapon but a test instrument. At that juncture, expecting to encounter very strong fortification on the Japanese homeland, the US planned to turn that instrument in an effective bunker cracker. One year later, the studies were still going on, when the end of the war put an end to the program. As a weapon, it would most probably not have been satisfying: range and inaccuracy were major hurdles it had not yet overcome.
The mobile mortar was capable of hurling a 3,650-pound projectile a distance of six miles. The giant mortar had a rifled, 22-foot, muzzle-loading tube which, with its firing mechanism and other parts making up the tube assembly, weighs approximately 80,000 pounds. The mortar's base assembly, on which the tube rests, is constructed like a huge box and weighs 93,000 pounds.
While traveling, the mortar's tube and base assemblies each make up separate tractor loads. A complete "Little David" unit also included a bulldozer and crane with bucket shovel to dig the emplacement. The huge mortar can be emplaced in 12 hours, while the largest (820MM) known German artillery weapons were hauled on 25 railway cars and required three weeks to put in firing position.
