You did not say double or single bbl. I am assuming single, but..
Have it beaded and Parkerized. When it comes back, heat it up very warm to the touch and give it a good application(s) of Eezox or Corrosion X - and keep that treatment going into the future. Be sure to specify and get a fine grade of grit used - as in texture. Some places use coarse stuff.
If I ever get my LCSmith restocked, that's what I'm doing - and I have tanks and salts, tho not set up. Yet, if ever again. Hot salts are generally not good for doubles. It can be too much heat for the solder, especially on older guns. If blued, have it "rust blued".
Another (cheaper) option would be to have it beaded, then do it yourself with Brownell's Oxphoblue, either cold, or as above heated to very warm touch. When you get the finish you want, again hit it with the Eezox or Corrosion X. That won't be as durable as hot salts or Parkerizing, but is readily re-done as needed.
No experience here with other coatings- except paint on a stainless rifle bbl once. It is back to stainless.
Last edited by las; 04/27/20.
Should not be too expensive to have bead blasted and caustic blued/. Or grit blasted and parkerized. The time consuming part is the polishing to get that bright finish. Would look a helluvalot better than the lawn furniture paint job.