The meter-bore “Babylon” supergun that ballistics genius Gerald Bull was building for Saddam Hussein prior to Gulf War I has, so far as I know, never been terribly well documented publicly. You’d think that there would be all manner of diagrams and the like available, but if they exist, I haven’t seen ’em. A few fairly uninformative photos taken after the war and a poorly reproduced photo of a display model are all I’ve seen.
The made-for-HBO-movie “Doomsday Gun” (which I recommend, it’s good) has a scene set at an arms show, with a scale model of the gun. I *assume* that the model was a prop made for the movie, not the real item, but you never know. And if it’s a movie prop, I don’t know how accurate it might be. Still, it’s the closest thing to a clear shot of the gun I’ve ever seen. Fortunately, the camera gets in close and pans along the whole length of the thing. I took screenshots all along the pan, and stitched ’em together, and it came out surprisingly well. The full rez image (which you can get by clicking the small one here) is fairly sizable.