I have shot TC Hawken and Renegades since 1980 and built quite a number of Hawken rifles myself.
I set them up the old way; I load 25 grain loads and shoot them into old pillows or cotton batting, I start out with a good heavy ticking patch and when i get a ball that show the impression of the cloth strongly where the land were and weakly where the groves were I start working on the load In a 54 I start with 90 grains and work up to 120 the I go back to the best group and see if I can consistently duplicate it.
If the patch and ball combination do not fit the barrel right it will never shoot really well. After the gun is broken in I start checking the patches if I find cuts in the patches I JB it with 100 strokes.I use Goex Black or RS Pyrodex and RWS caps because this combination has worked well for me. I have never been able to get a .530 ball to shoot up to my standards all my guns but one ended up with a .535 ball the exception took a .540. It is not easy to get a 2.5 inch group with iron sights at 100 yds and I can not do it any more because my eyes are not what they used to be but I could do it until I was in my 60's, now I have to use a scope. If you ever have the opportunity watch the Hawken and Mountain man matches at Friendship IN, you will see the guys shoot groups that are only 17 inches string measure. [ That is each ball is measured from the X and the measurements are added together.