Either a 75" or 86" twist .004" deep rifling in the .72 will shoot just fine with most loads you are likely to shoot - if the load is tight enough. It usually takes someone of experience in muzzleloading shooting to be able to load the combination I am referring to. You cannot load a tight load in any Pedersoli rifle without re-crowning the muzzle. The edges are too sharp and need to be smoothed with emery cloth or paper. The end of your thumb is the correct shape for this - rotating your thumb shoved into the muzzle and rotating the barrel periodically to ensure your 'grinding' is symetrical.

This rifle sounds interesting and front and rear sights, if not screwed into the barrel, are easily replaced with good dovetailed sights and leave no trace Pedersoli origninally put stupid sights on it. Google "express sights" to find a good set. There are a number suppliers of a variety of sights. I suggest a standing sight with 1 or 2 leafs.

It takes a considerable quantity of powder to exceed about 12,000PSI in a 12 bore - most likely more than you'd want to fire in a 9 pound rifle. Now, what the Italian proofs for max charges are, I don't know. Any time you go above recommended charges, which guys I know do in the doubles, you are on your own.

WW balls only cast a thou or thou and 1/2 larger than pure lead. The reason they are difficult to load is they are toohard to engrave by the lands, and the grooves are very shallow, not giving much room for the cloth.

I would suggest a .705" to .710" mould from Jeff Tanner & you should be able to load both WW or pure lead balls from it with a .015" to .020" patch. I am suggesting the smaller ball due to the shallow rifling and the need for a thick enough patch to hold substancial lube for keeping the fouling soft. Panty material (thin) does not make good patch material, btw.