Waco, thank you.
Now that makes a great deal of sense. The bore was originally .660 and when it was rifled it was opened to .690 or so. I did fire it with patched ball and have loads with a full size ball but haven't tried them as of yet. Really a tremendous amount of power over 150gr of black with the almost 12 ga ball. If I can get to to group into 2" at 50 yds I'll be happy.
I think that it's feasible.
Now just have to take it out for pheasants in the fall...

Tom

Carbonation without fermentation is tyranny