I thought it best to start a new thread in which the discussion is "centred " [ pardon the pun] on accuracy. As I've mentioned before, smoothbores need to be tested with various combinations, much like rifles, in order to find the sweet spot and achieve their accuracy potential.
Many years ago, I made the decision to hunt exclusively with a flintlock firearm. That was a learning process, what with the inclement weather we face here during the hunting seasons.
Today, most of the time I carry a smoothbore, and it took a lot of testing to get to the point where I was happy with the results I was getting.
I just went through my Muzzleloader magazines and found an article in the July August 2015 issue which was an eye opener for me. It is written by Mike Beliveau and titled " Old School Smoothbore Loading - Round Ball "
I won't go through the article, but in the end his Fusil 20 bore , using .610 balls and a 90 gr powder charge had a group size of just under 8 inches at 50 yards. When he bumped up the charge to 110 gr, the group at 50 yards shrank to 3 inches.
5 more groups verified that this load was consistently within 3 to 4 inches .
It may take a lot of work at the range to find out what your gun prefers, but it's worth the effort.