Both Cerakote and Duracoat are real steel firearm finishes. If they are good enough for the real thing on deployment in a warzone then I think that they will suffice for Airsoft. That being said, the will wear a bit but in my experience, most people prefer that look of authenticity.
If you are looking for something that never has any signs of wear then likely powder coating would be best. Be careful though in that the thickness of powder coating could alter the fitment of your parts.
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