They had one of these on the History channel last night and fired it. It was a breech loader. They fired the stone ball through a replica ships hull. In the berm behind the hull they found the stone ball...well half the ball. When you were on a ship that go hit with one of these you had to duck wood splinters and stone fragments
I remember that show. It was great. I thought about doing a breech loader but muzzle loader with a shorter bbl was easier to make. I still have not given up on the idea of a breech loader but my youngest son want me to do the Puckle gun next. Yes a Puckle. I got all the references I could find and drew it up 4-5 years ago. I am going to copy the missing one as it was all iron and smaller bore than the others.
If anyone does shoot stones, caution
they bounce I have not shot any at a solid target in 25 years. I shot a load of stones at a wooden backstop with my first gun( 2" deck gun) about 25 years ago. My dad 83 and a WWII Airborne artillery vet rembered this and talked about it yesterday. That really surprised me. He does not remember the exact number of jumps he made (13th and 82nd Airborne) but remembered the stones crashing through the backstop. We were a long way away behind a sand bank when it discharged.