Dave C., I am envious of your cannons! Served on a cannon crew in NSSA meets, early 60's, we had a barrel made from a length of 3" naval gun - rifled, mounted on a naval gun carriage. Shot beer cans filled with cement at 500 and 1,000 yard ranges. It was pretty accurate.
So, I have to enjoy yours through your pictures and writings - please keep them coming. Right now, I don't even have a range to shoot all my ML's!