Agree with PA-Joe up to a point. I have a TC Hawken in .54 and it likes 105 grains of FFg. I know I have a little powder thats not burning but I am shooting a 3.5" group at 100 yrds. with roundball. I use .535 rb and cotton patch lubed with a soluble oil.
So you understand how I got to a light denim patch material and soluble oil. Several years ago I was having accuracy problems. Sometimes I would get 4" groups at 100 and other times my group was right on at 70 yrds and 16 inches low and 10 inches to the right.....go figure.
So, I spent what was the best $15.00 of my life. Check out Dutch Schoultz's web site
www.blackpowderrifleaccuracy.com. I learned a few things that I flat did not know. What I gained was how to put it all together.
Lets put it this way, I killed a 18 month old cow buffalo at 80 yrds last year with a roundball. Pass thru with both shots. 3 yrs before I was in Montana sighting in for a bear hunt when I found out I was dead on at 70 and WAY off at 100 as described above. Never could duplicate that problem when I returned to Indiana, and by the time I went back in the fall, I was using Dutch's info and I was dead on at 100 yrds.