The only camo barrel I own is a Benelli SBE used for turkey and always figured the finish was anodized or heat treated and more than just a painted product. The solvents I use to clean a shotgun are different that probably what that guy used for his ML. I would be curious to find out what he used. If I see him again I'll ask. Both of my ML are TC and both have blued barrels and wood stocks. I felt bad for him because it is a nice gun. If it were mine I would send it in for repair.