A buddy of mine had a bowling ball mortar that was on a base plate about 2 feet square, the mortar itself was only about 22 inches long, but it had side walls about 2 inches thick. It's inside looked just like a bowling ball radius with a little hole for the fuse. There wasn't a powder section like on the one shown in the video above. He had it in his garage storing it, and he wanted to get rid of it because it weighed around 200 pounds and wasn't practical. I never saw it in action, but he said they would take it out near the Columbia river that runs between Oregon and Washington and shot it on some BLM land near there.