I can't answer that specifically, but just spoke with a gunsmith who is in the process of refinishing a Perazzi MX-8 for me which was imported by Ithaca in the '70's. All the case color was gone, right down to gray metal, which would not look too swift next to a total re-blue on the rest of the gun. He got me to agree to let him blue it as well. I don't know the composition of the steel in that receiver, but last time I spoke with him he said it was soaking in an acid bath. If I have opportunity I will ask him what he used to do this, and what blue.
