PATINA!I can tell you what *I* think it is: surface rust.
I just dont know how it is getting there. I keep the gun well-oiled with Barricade.
You can only see these spots when viewed at an angle (like in the picture), not when looking down the bore. In addition, any patches I send down the bore dont pick up any brown (from rust)
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How should I go about removing this?. I've got some Ballistol, and I've been reading about how it can "get under" surface rust and make it easier to remove. Should I soak a patch in the Ballistol and run it down the bore a few times?