If you scrub the mark until it's gone you will wind up with a finish that shows where you scrubbed.
Leave it there and wear it as a badge of courage! Be glad its a small fault....it could be worse.
To fix gun blemishes you must refinish them. That will cost you a minimum of $250 including shipping and labor.
Its a gun for Christ's sake. If you take a safe queen out of the safe.....it's no longer a safe queen.
(Riveted pant pockets with a sports coat? You deserve to scratch your gun.)