Be aware that due to harmonics, one can ALWAYS find at least 2 powder charge levels (a low to medium and a high) that give the best inherent accuracy of the barrel as fired. On longer barrels one can often find 3 different charges.I think you should spend several days experimenting with patch and ball thickness and then powder charges until you find the powder charge that gives you pinpoint accuracy.....
Here's how to do it ...
https://www.muzzleloadingforum.com/...d-development’-to-find-the-best-group.169960/