I'd follow the previous advice to have the bores checked and measured by someone who is competent and has the correct tools. I looked at a 12 ga. gun on Gunbroker last night that the seller says has .750" bores. That thing is already about half way to being 10 gauge. Who knows how much pitting has been struck off the exterior of those barrels? Imagine what some more honing could do. A lot of these old guns have been screwed with by fools before they find their way into our hands. You've got 10 fingers and 2 eyeballs. Try to keep it that way.
