Painted = not durable
Coated = reasonably good.
I have used Duracoat, KG Gun Kote, Cerakote and Brownell's Alumihyde. All with good results. For Aluminum and Steel, I prefer Cerekote, with a slow bake. KG Gun Kote #2. Duracoat is my go-to for synthentic. I use it on stocks, like McMillan and Magpul PRS all the time, with great results.
one dog's opinion. Like belly-buttons, we all have one, and not sure why.