Point your browser to the ONTOS web site where you can read about how we used what has been called the Worlds Biggest Shotgun.
I worked in Battalion Maintence and had 45 of these "things" (ONTOS in Greek means the thing) each equipped with six (6) 106MM recoilless rifles to maintain. Your post reminded me of that one of my jobs was to make sure that the spotting rifles (50 Cal), 106's and the optical sights were all lined up on the target. Our test range for that purpose was 3,000 yards and the targets were empty 55 Gallon oil drums. Once the sights were in alignment a good gunner could put one of those 106's through the drum nearly every time.
Keep in mind that the 106 was a direct fire weapon. That means ya gotta see it to hit it. But, with an aiming stake, a gunners quadrant and a device to fire the rifle from a distance, targets out of sight have been destroyed.
Semper Fi
An Old Man
That looks like something I can make in the video game Chromehounds.
Tracked, wheeled, legs, hover base; rocket, automatic rifle, sniper rifle/cannon, high-angled stuff... haven’t played it in a while though. Mostly because I was kinda bad at it.