I have a Browning Gold 3" hunter Slug Gun that has been working great. However everytime I go through the cleaning process, I see more an more sooth and black residue build up on the magazine tube under the gas seals. Is this an indication of fualty seals? Or is it normal wear and tear of the polymer seal rings? The black residue is very hard to remove :x . I have been resorting to chemical paint removers to disolve it, since it seems to be more like melted O-ring or rubber material than unburned powder or etc.
Any suggestions on how to remedy this problem if it is actually a problem, and cleaning tips will be greatly appreciated...