To Answer your question, which is difficult without a picture or being able to look at the gun, is to.
Draw file to get rid of the pits (and rust). Then spin it on a belt sander, starting with 120 grit and ending with 600 grit, (or if you want a deep blue, work your way to 2000 grit)..
This works for round recievers and barrels, but buffing wheels need to be used on none round parts after draw filing.
Then throw it into the blueing tanks, taking into account bluing will maginify any defects.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071