I just got a new BCM BCG and was taking it apart to clean. After I was done, I was using a brass punch to push the extractor pin back into place when I slipped and it scratched the bolt. The scratch is not deep enough to have damaged the metal, but it did remove all the finish down to the bare metal along the scratch. Will the bolt rust there now? Should I get one of those Birchwood Casey Black pens or is it no big deal and I should not worry at all?