To get a high polish, deep mirrored blue job I spin the barrels against a belt sander.
Depending on the condition of the barrel I start out with a 320 grit barrel and work my way up to a 4000 grit barrel. I like the effect of a bead blast action and a highly polished barrel then into the bluing tanks. After that cold water dip rinse and then clean it with lots of WD 40, followed by a heavy rubbing with RIG.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071