Will it only accept .520 balls? Those are hard to find now and Lee no longer makes a .520 mold. My bud has a Pedersoli Tryon rifle with a 53 caliber bore and balls are hard to come by. He has a couple of boxes of .520 balls from Hornady left but I don't think Hornady makes them anymore.
If your not selling or asking about buying this rifle there's no reason you should post on the classifieds.
If you have questions about things not the rifle send a PM. It won't hurt your post count that much.