If it's anything other than small scraches like screw driver marks on screw heads it needs to be done by a gunsmith (hot blue) if you want it to look good. It will run you naywhere fron $100 to $250 depending on if you simply want a bead blast or all the way up to a "mirror" finish.


Another option that you can look into if this is a hunting rifle is parkerizing. It's a flat black finish that is an actual molecular bond between the chemical and the steel. It is more durable than blueing. That will run you in the neighborhood of $120.