I've had really good luck just using that spray paint for grills/wood stoves on all the firepits I make and sell. Especially if I paint them while they're warm or hot but even if not, it's held up pretty well all things considering. I've had no complaints from customers on the firepits I sell and my personal one has been outside for about 1.5 years and I did a piss poor job painting it and it still looks decent.
I'd say it's listed in the Random Pictures, just in the last 2 days. There was a homemade fire pit, & so far the #1 is Rust-oleum high heat Something.
WAIT:::::::::: That was Your fire rims & Your Paint!
Rustoleum has a ultra-high temp paint that sprays as a powder. The can says to bake it on the part if it doesn't see heat. I've had it on some headers, exhaust manifolds, and other exhaust stuff and it's been there for many years.
Okay, we'll check Rustoleum ultra-high temp paint. We'll work on my uncle's exhaust system next after we finished installing the rotors and tis wheels on the truck this weekend.