As the makers did originally .Then again it is up to the individual . Polishing barrel flats is a matter of choice in MHO and guns that have had several sets of proof marks often look better with them blacked .W&S only polished flats on the 701 as were the action flats and face .Flats are often polished for the fact that the blacking is no so good around the lumps or that someone has slipped and marked them when cleaning off. Happens to us all thinking of the hundreds I have done .