What kind of primer?
If you're looking at the roller and tip method peddled on the Internet, you better like sanding. I give it two thumbs down.
Any paint product designed for professional refinishing will be far too thin for a roller or brush. Save that for Rustoleum.
I often brush epoxy on parts that I intend to let sit for a while. I do it to protect the parts from corrosion while they sit. When I am ready to install the parts and refinish them for real, I sand it off and spray epoxy for a first coat.
You are the one you've been waiting for.