I have a gas block whose original finish (looks like parkerizing) is worn off in most areas. I was wondering if any other M4C members have any input on what the most durable/long-lasting/heat-resistant finish is for application on a gas block?
Thank you in advance!
On cut down shaved gas blocks I just refinish them with high temp BBQ paint. They are under a hand guard so no one really see them. It does work pretty well though.
It’s for a piston rifle and is external. In all honesty, I want to prolong its life and condition as much as possible because of that 
Bacon grease works well. Nice patina and smells good.
Cerakote makes a high temp version in satin black now. I think it’s good to 2000 degrees.
How much do you want to spend? For big money you could send it out to be nitrided. For a couple dimes’ worth of paint you can repaint it with something that will color it non-shiny and prevent corrosion, which is all you probably need. I’ve used both BBQ paint and automotive engine paint. BBQ paint is rated to 1000 F. which exceeds anything you should need, and it requires no priming - but it doesn’t seem all that resistant to abrasion. Duplicolor brand engine paint is rated to 500 F., which should still be plenty (unless you do mag dump after mag dump), works fine without priming in my experience, and has very good abrasion resistance - better than any other spray can paint I’ve used (of any kind or purpose). A spray can of Duplicolor runs $6-7 around here, and it’s available in various blacks and a “cast coat gray” which is a nice dull medium gray. BBQ paint is a little cheaper and the flat black I tried was dead flat and more of a charcoal color than a deep black. Either one should be more than adequate. Whatever you use, get the part completely clean, degreased, and dry, and follow the paint can directions.