You may want to check the S&K website, I believe they also have traditional split ring for those bases. Not sure and have no experience with them?
As far as case hardening that I don't know either, best ask an expert? The rings seem to made of a soft malleable steel and maybe case hardening will make them brittle?
I've never seen those case hardened.
They are about the slickest rings going.
What's the story on your rifle?
Shrap, I'd call the company and see what they think. Those get bent a good bit, fitting them on the scope.
DF