most lately construction of similar kind of gun was attempted under Saddam “▇▅▆▇▆▅▅█” Hussein as Project Babylon. it didn’t work because required high pressure pipes were intercepted and head engineer was assassinated

this was done by the same guy who, at first try, wanted to send satellites to orbit using a giant gun, as DoD Project HARP. it also didn’t work, but at least it was useful for atmospheric physics research