Cold blueing is in no way comparable to a good hot-blue job, and if that's what you are expecting, it's just not gonna happen. If you are getting shading and streaking problems, it may be the base metal, and/or the preparation. Fine sandpaper and steel wool sound awfully crude for any type of quality finish with anything. A good buffing with various grit compounds and wheels followed by a proper degreasing is generally what's needed. Eastman Co. makes some nice kits for this work. Have you considered giving it a coat of flat black paint??