I got a customized Ruger Blackhawk that had a scratch along the barrel and I wanted to fix it. Well polished out the scratch and then had to reblue the area. So got a cold blue kit and first cleaned and de-greased several times. Then reblued the area about three times. Think it turned out out nice. First is the polished area and last is the finished gun. Was easier than I thought. Just did not rush it. Next will refinish a sawed off shotgun for brother that was neglected but very functional for a truck gun.