I have never had a problem with Oxpho bluing not working when done properly. Are you sure that the sight is not stainless? Try a magnet on it to see if it sticks, if it does you are ok. Try heating the part after cleaning it with alcohol. Heat it until it is warm, not hot. Then try the Oxpho. Apply the bluing then wait 1 min. Use 4/0000 steel or bronze wool to buff up. It may take 5 or 6 coats.
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Tom
NRA Pistol Inst
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