Going to polish my Gen 4 21 barrel today. Its at about 4.15 hrs in its vinegar bath (distilled white vinegar). Instead of using scotch BRITE or sand paper going to use some good ol fashion elbow grease and a rag. Might hit the feed ramp with some emery coth depending what it looks like after I get the bluing off. And of course the secret weapon Mothers. Ill be going with the hand method over the dremel, ive got one but hey call me old school.