I have a old 7mm mauser that shoots J word boolits ok but it has a dark bore that just won't clean up. I started shooting cast through it and have had erractic results. I looked closely down the bore and the rifling looks great but the lands were grey-black and rough looking and I have been trying to shine and smooth them up. I tried lapping the barrel to get to shiny metal, no luck. I have shot 30 cast lapping bullets ( .289 dia cast rolled into valve lapping compound with the lube grooves full of compound in front of 10 Grs. of 2400) no luck. Today I tried a 50-50 mix of vinegar and 3% peroxide and soaked the barrel for 10-15 minutes then ran patches and a bore brush with #2 steel wool, no luck. I soaked the barrel at least ten times today and every time I pored the compound out it was a reddish brown color but doesn't appear to be rust. The first patch comes out with dark gray- black fouling but no indication of the reddish brown mix. It looks like water when I pour it in. I have spent 8 hours working on this today and ran at least 100 patches. here is a picture of the once clear solution and a couple of patches. I think I could do this for the next 10 days and still have the bore be dark . It looks almost as if I am trying to shine up pencil lead.here is a pic of solution as it comes out of the barrel. After all that I relapped with lapping compound and It looks the same as when I started!! Do you think the reddish color is a chemical reaction with some old corrosive primer compound?![]()