![Image](http://www.public.iastate.edu/~jessie/PPB/Highwall%2045-70/JB%20patch%20from%20Highwall.jpg)
This patch was soaked with Hoppes #9, then some paste was worked into it and 5-6 roundtrip strokes were taken in the bore of one of my rifles that has been giving me trouble. This was done 5 times and this is the third patch. Prior to all of this, the bore patches very clean with a dry patch, or a solvent patch, or a water-wet patch. The bore also looks clean in a bore scope.
Is this just barrel metal or is this carbon fouling?
This rifle has never fired a lubed bullet or a grease cookie of any kind. Only paper patches with fiber or LDPE wads. It still shows reamer marks after 10K rounds at least, and the throat looks great. It is lubed with NAPA ATF - F fluid which is wiped dry before firing. For a decade this has been fine until this year.
Looking for ideas about how to interpret that patch. They didn't get much better before I quit.