I figured it out finally.
For the last three range sessions with my blackpowder muzzleloaders, I was using a nylon bore brush. When I began cleaning the guns the other day, I found a unopened pack of phosphorous bronze bore brushes.
Every time I wiped the bore tonight with the nylon brush, patches came out white / clean.
Every time I used the brass bore brush, patches were dirty.
The oddest part to this is the nylon brush is tighter inside my bore and will not clean good. The brass bore brush goes down the bore relatively easy and cleans like a champ.
End result?..... a dirty bore accumulation after the last three range sessions. What's the lesson learned here?...... don't buy nylon bore brushes for your muzzleloaders.
I'll finish it tomorrow with the JB Bore Paste. I can see the Finish Line Ahead. Thanks to everyone that replied, for all your help.
