Years ago, I turned a wooden pattern for a black powder cannon, using a metal-cutting lathe Getting all the major and minor diameters for all the various, and decorative, barrel moldings became very easy. No dips, no wavy straight sections. The taper for the barrel was also easier to generate than on a straight, ordinary wood lathe, and I didn't have to play catch-up with constantly repositioning, and adjusting, the steady rest. The OAL of the barrel was around 20", and I had the cannon cast in iron. Then it went to South Bend Replicas to be bored, and sleeved. The whole process cost me big bucks, between custom-casting, machine work, wood for the pattern, and Oak for the naval carriage. Forget the shipping charges! It turned out to be a nice project, but cost a small fortune. I shot the cannon on the Fourth of July a few times, but the neighbors wet their pants when it went off, so the shooting stopped. Fast forward....25 years later it's now collecting dust. A very heavy, knick-knack.
Frank