I have several Pedersoli 45-70 rifles that take modern loads. One Sharps rifle and two Rolling Block rifles.
Varget, H4895, H4227, H4198 and 5744. I used 300, 480 and 535 lead bullets. Very few jacketed 405's.
All shoot well with the right formula for each bullet.
I shoot iron sights and we have fun with Potatoes out to 150 yds. 1"-2" groups @ 100 yds is easy enough. At 600 yds 6" to 15" groups is common depending on the day with a 5" being the best.
The reason for so many powders is! Use you you have.
Note: the Pedersoli rifles love 405 gr and up. 300 gr are for short range only.