Bronze brushes and Black Residue

[Howard]

Further to Josh's post a couple above.
I have found too, that you can indeed scrub with a bronze brush and Hoppes, and get a following clean patch, devoid of any blackness.
I've got this on two 6mm barrels so far.
Interestingly enough, I feel that other means - hot water, Bortech Eliminator and JB Paste have contributed to this clean state.
It's the thought though, that blackness on a following patch is other than carbon, which is false.
I've had a look at both crowns of the barrels through my 40X Stereo Microscope, and I can see no sign whatsoever of any marks caused by the bronze brush being drawn back through the barrel! There are the original slight circular machining marks of the crowning tool - whatever it may be - but there are no marks aligned with the bore.
I would think that if the brush damaged the bore, it would damage the crown too, as it dragged back over the edge.
This sort of negates my thought of my last post, that bronze brushes probably damage the bore.
Note that, this is NOT bronze brushes with Pastes, only with Hoppes or Eliminator.
Perhaps Pete and DaveMc might have another look at their test piece which established the cause of the barrel failure, i.e. a non rotating brush with paste, and see if there are marks on it's "crown".
Howard.