I have no experience with Baker Batavias, but I have seen barrels that had that, too. I always assumed it was the result of many years of shells fired without a plastic shotcup. Human fingers are pretty sensitive to indentions and bumps. If you can't feel anything when you try, I'd be inclined to think they were not cut, but rather the result of years of use. I'll bet it would polish out pretty easily.

SRH

May God bless America and those who defend her.