Your old Renegade is a fine rifle. And I am willing to bet it has a 1:48 twist. Your barrel should shoot Powerbelts just fine. You may also want to try some 300 grain .430" Hornady XTPs and Harvester Green Crushed Rib sabots (50 cal for .44 Bullet).
I assume your rifle is a percussion cap so you may want to push that bullet with either FFg or Pyrodex RS. Start at 80 gr and work up to 90 and 100 and see what shoots best for you.
Good luck.