How bright does a receiver need to be to case harden?
Don’t know but might suggest you contact Tyler Gun Works in Friona, Texas for the case coloring: tylergunworks.com. They do awfully nice work. Also rust bluing and nitro bluing.
I polish to 400 grit and blend out with a fine wire wheel before hardening. If you are going through all that consider having your engraving picked up first. It would not add that much in terms of cost to the job and will make a huge difference it the outcome. Good luck Rick.
Steve
Are you leaving the nicks and pitting?
Yes the nicks and scratches will remain.
I went the other way with restoration of benchmark Sterly, Rick. Wouldn't risk case hardening of action, on advice of one of the best gunsmiths in the country.
The higher the polish the lighter/brighter the colors and the more the blemishes stand out.
I'd just dob a little bluing on that and forget about it.