Have you considered using any of the spray on finishes?
They come in a variety of colors, and seem to last pretty well.
(Plus they are easier to apply than parkerize or re-blue)
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
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Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)