Firearms, or something bigger? There are Melonite coaters all over the place. Yahoo should make short work of that inquiry...
Something larger but...
Unless the EPA rules changed when I wasn’t looking, ferritic nitrocarburization (Tenifer/Melonite) is actually illegal to perform in the United States. If that’s changed, then good. One less thing to have to ship out of country.
My point is this - there is so much that can no longer be legally performed in the United States due to idiot regulation and legislation, some of us who make things and have to compete with others *have* to ship stuff overseas for processing because we *can’t* get it done here, for any price!