I have a Ruger Red Label 28 gauge that the chamber portion of the barrel and upper lever are turning purple or plum. The barrels themselves are fine. I contacted customer service and they weren’t much help, said it was pretty common on older firearms and it could be reblued but couldn’t guarantee it would cover the plum/purple. I don’t really consider this an old firearm 420-serial number. They didn’t say if the reblue was on their dime or mine. My questions is the plumming affecting the value? Would a re-bluing work and would that affect the value?