Draw filing.............followed by a good polishing.
Nothing beats a good belt sander after Draw Filing. Start our with course grit and work your way down to about 2000 grit, depending on how you want the fininsh.
Remember after you throw the gun in the bluing tanks, the new bluing will maginify any scratches or imperfections you left.
With a little care and effert a belt sander will put a mirro finish on a piece of gun metal.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071