Nice looking gun! Have always liked the British term "Household Artillery".
Turned a .75 cal Rodman style a few years back- had a 16" length of 2.5 " Phosphor Bronze that was scrap from another project, so thought- why not? Mainly for saluting fire, but would hum a 12 g slug thru a 2x4.
Did get a grin, tho- walked into a gunshop, bought a length of cannon fuse (used by a lot of makers of illegal fireworks) Fellow customer looked at the fuse, asked "Now, what do you want THAT for?" Looked at him, smiled, and said "I want it for my cannon. What else?"
Ref: Cold forging the trunnion straps- I cheated. 60 ton arbor press, and a swage block.