BR,
Thinking about this some more, you or one of the regulars attached a list of all the parts of a Krag with each individual finish type noted. The receiver and loading gate were both case hardened finish if I remember correctly. The details on the cutouts are machined with very consistent chamfer sizes and vey good finishes. I am think the parts were pulled from production before heat treat allowing the machining to be done that smoothly. If this guess is correct then regular bluing would be an appropriate finish. As clean as the edges on the bolt cut outs are, I would expect it was not heat treated either. If I was doing this at SA I would have pulled almost good parts out of the discrepant parts pile and done the cut outs on soft parts.
An engraved plate showing who this thing was made for would have been appropriate, with none on the wooden base it looks like an almost delivered piece.