W9 (nuclear warhead)

The W9 was an American nuclear artillery shell fired from a special 280 mm howitzer.

The W9 was a gun-type nuclear weapon, using around 50 kg (110 lb) of highly enriched uranium in one large rings assembly and one smaller bullet, which was fired down a tube by conventional explosives into the rings assembly to achieve critical mass and detonate the weapon.

[citation needed] The W9 units which were retired in 1957 were recycled into lower yield T-4 Atomic Demolition Munitions.

The W9 artillery shell was test fired once, fired from the "Atomic Annie" M65 Atomic Cannon, in Upshot-Knothole Grable on May 25, 1953 at the NTS.

Subsequently, the W33 nuclear artillery shell was test fired twice (not in a gun) during its development (shots Nougat/Aardvark and Plumbbob/Laplace).