Well cleaning your ML can be sometimes a challenge! But my question has to do with oiling or lubricating the bore when it is clean and dry. I know there is a lot of controversy regarding the use of Bore Butter or WonderLube but I have never had a rust issue when using these products. Yes I do realize that Colorado is a much dryer state than others so no rust! I sometimes use Balistol or even Remoil but I do know that petrolium products and real black powder don't mix ! But when using a traditional grease often times the patch comes out black and dirty. Not all of my ML come out this way, but some! Has any one else experinced this problem with there guns?? And why do you think this happens ? Thanks for your help with this confusing problem.