I can understand your concern for the BC of different conical bullets. But to be honest, I could care less about the BC in most cases. You are shooting an open sighted traditional rifle. So you are going to have to decide just how far you want to shoot and what you want to shoot at. For instance, deer are not that hard to kill. Even a 70 grain load of powder will kill deer at most open sight distances. Hunting something larger, then you have to start looking at the weight of the projectile.

You have a 1-48 twist. So it will shoot roundball, conical bullets and even sabots. If the Lyman is like mine, they like between 85 and 95 grains of powder. Good luck with your new rifle. It will be interesting to see what you discover.