I shoot an old CVA MT Rifle 28 yrs old, 34" 50cal. For ELK i use 90 gr of fff with 275 gr TC maxi hunter, killed 14 with this load, only one animal went over 30 yds. One important thing to know and remember 95 % of the animals shot with a muzzel loader will not leave a very good blood trail if any at all. this load works for me just have to find out what your old girl will shoot the best.
Big and fast isn't always better. Shoot well