Carl cold blueing for the most part is for small areas and will probably not give you the results you are looking for. it will continue to have rust spots. the best way is going to be finding someone who can hot blue it for you, or try some of the spray on coatings like DuraCoat or others. part of the problem with cold bluing products is not getting an even coverage like being able to immerse the entire part into the blueing solution. from what i understand the Oxphos from Brownell's is probably one of the best cold blueing solutions and if you have a way to immerse the entire part to blue it, then your results will be much better. good luck.
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