What load are you using, Dave? About 1/2 pound of 1F? Sure is a splendid looking piece.
Used to shoot a cannon in NSSA, but that was years ago. Fellow who worked at Anacostia had a 5' section of a 3" 50 cal, with really great rifling. We would go to A.P. Hill or Ft. Meade, shoot concrete-filled beer cans. They were steel back then, so yeah, long time ago.
With a pound of cannon powder, we could hit a piece of plywood - sometimes - at 1,000 yards. I was the sponger. Had it on a naval carriage, as we were the "landing party" off the Constellation.