I have just started using this method this year and testing is so far so good.
http://www.eabco.com/MuzzleLoader02.htmIf it has been cleaned I take the clean oiled barrel and clean the oil. Wipe with a T7 patch then a dry patch. So far my first shot has been in the group with the other shots on my Omega and my Dad'ss Optima. It will take more time to make it conclusive with me but looks promising