Original Krag receiver finish?

[Two-Dogs]

I went to our local library hoping to find Brophy's book but they didn't have it, they're searching. I was wanting to know what the finish was of an original Krag. Both of mine have a silvery look like most Krags. To me it looks like case hardening when over time it fades out. Were they Blued or Case Hardened.
Thanks

[Dick Hosmer]

Case-hardened.

[Two-Dogs]

Thank you