Fired MANY times

[mrerick]

Which all comes back to the best advice I've ever seen regarding used firearms:

Believe the gun, discount the story.

Clearly the more experience you have judging a gun by appearance, the better off you are when buying a used firearm.

If you really were trying to be deceptive, you could have easily cleaned all the carbon away using a mild polish. That would, of course, been detectable too for one skilled in such observation...