Douglas, We are pretty sure he polished this piece a bit AFTER we tested it in the pit behind the 5 Ft. diameter Cottonwood, not before, but we worry about those bronze signal guns near the main flag pole on those Army posts I was assigned to.
Cannonmn, 100 grs. of Goex Fg BP is NOT excessive for a 75 Cal., six pound cannon. No patch or wad was used. The ball was a rattle fit in the bore. For everyday firing of a well cast bronze gun in our experiece, 60 or 70 grs. is a better target load for a six pound cannon of this bore size. With a breech wall thickness of 1.0", a solid, bronze gun of this size should stand a proof of 200 grains of BP easily. I don't know how to explain the porosity present in this casting other than to say, with no exaggeration, that, when we drilled the bore, the surface inside was about 50% air and 50% bronze. Now is it clear how compromised this gun's metal was??
The outer metal was much better than that in the gun's interior. We think that this fact could contribute to the hinge-flap effect of the single, blown piece.
EL Cazador 66, You are certainly welcome and thanks for that recent post of those ancient artillery pieces that Dom made for you. He certainly does a might fine job! We love his cannons.
Mike and Tracy