If your receiver was case colored it should be aneiled then recolored either blue or cased. You will never get a good rich color with out softening the receiver.
If you are not going to get your receiver properly & expertly "Re-Hardened" do not under any circumstances anneal it. Just because the color is gone doesn't mean the hardness of the case is. Maintain that, which annealing would destroy. A proper re-case hardening would likely cost more than this gun is worth unless it has "Very Great" sentimental value.
This would be the type of gun on which I might recommend the painted on "Faux Case Coloring". This is done by "Warming" the frame to about 165°F (well below boiling water temps) & then daubing & streaking it with cold blue on a Q-Tip. I have done this on a few low cost guns & it is about as good as one can do without spending a lot of money on it.
This was the method recommended by Ithaca in one of their service manuals I have on the Perazzis they once imported. I believe the frames on those guns was made of a heat-treated alloy steel which was unsuited for convential case-hardened colors. Even the original factory finish was not true "Case-Colors".
The ones I tried it on had been previously case hardened & it worked good on them with no need for annealing.
