I have seen pictures of Krags with deep bluing and I am with Paul on this " For me, a deeply blued Krag just don't look right!" If he had not already said it, I would have.
Maybe I am a worry wart, but the case hardening layer on a Krag is only so deep. If you polish off .005 thickness every 50 years to reblue, pretty soon you will have a piece of junk with no case.