LMF browing chemical from (track of the wolf) : I just finished a Renegade Flinter in 54 cal that came out super: follow the instruction that come with the bottle ,I found the best results is to just dampen the chemical on the barrel and let sit for about 12 hours ,then reply before carding .I used a old blue jean material to card.
I would say it took about 8 to 10 coats total for a dark brown
Remember do not apply the chemical to heavy I found a small cotton cloth about 2 inch square works well ,try even strokes from end to end