There are some muzzleloading cannon forums included at some black powder forum sites. There seems to be alot of them on ebay and some other auction sites. My 1984 CVA cat calls it the Old Ironsides, 7.5 inch rifled barrel, one inch wheels, 2.75 inch overall height 7.5 inch overall length and weight 22 oz. finished list cost back then was $41.95 and kit list was $36.96
All that being said. I was at a range near Davvisonville, MD many years ago. It was a black powder club and you could pull your vehicle up to within about 15 ftt behind the loading benches. A guy pulled in with his fancy customized van and parked side ways so his van was perpendicular to the range. He even had etched glass windows on this van. He and a buddy brought a little Old Iron sides cannon to "try out" Well they loaded it up on top the loading bench. When the fellow lit the fuse, he pushed away for the loading bench and it wobbled. As he and his buddy backed off and away, the cannon slowly rolled backwards, and tumbled off the loading bench, pointing straight backward. It put a hole through the fancy glass in the sliding door and a huge ugly hole and dent in the other side of the interior of the van.
The stooooooopid things some folks do. They are not toys.