Some time ago I promised to myself (and announced to everyone else) that I will limit my "creative" work within FD department to finishing some earlier started project (most importantly Polish Wings), but I decided to make this one-off exception to this principle and venture into area in which I don't have much experience. I believe, though, that the result isn't so bad.
M65 Atomic Annie - or more formally: U.S. Army Gun, Heavy, Motorized, 280mm, M65
- was the USA - and world's - first artillery piece capable of firing nuclear shells (with 15kt W9 warhead). It was developed in late 1940s and early 1950s and introduced into operational service in 1953 in US forces in Germany and Korea. Developments in the missile and nuclear technology - like introduction of nuclear-capable tactical ballistic missiles and nuclear shells of 203mm and 155mm calibres - made the Atomic Annie relatively quickly obsolete, but because of it's PR utility it was retired from service only in 1963.
The whole system had a length of 25,98m and weighed 78308kg, including the cannon itself 42589kg. It was capable of firing projectiles weighing 274kg to a distance of 28,7km (31400 yards).
USA, M65 280mm Atomic Cannon "Atomic Annie"
Note, that the barrel was actually capable of much larger elevation (and my source actually showed it with such), but for the ease of drawing I limited it to 45degree.