YES try ff instead of fff
Yes I've a very old and slower twist .45, and for some reason it shoots better with 2Fg. So why not try it.
Also for Pedersoli, check your patches. They sometimes leave burrs on the egdes of their lands, and cut patches. I had a Pedersoli Frontier sold as a Cabela's Blue Ridge Hunter that shot conicals well, and would also shoot patched round ball at 25 yards into the same hole, but at 50 yards it was a 6" group and not on paper at 70-100 yards. When I looked at the patches I had from 4 to 6 holes corrisponding to the lands, and after some polishing of the bore, it shot patched round ball very well.
LD