My finish of choice for metal has been the "Gun Kote" The only way you get it off is to sandblast it. You can run it through a air brush, camo patterns as well. 300 deg in a oven for 1 hour is the cure time. I have done several 45 autos, rifle actions, works good and is very abrasive resistant. You can get it in almost any color.
Gun Kote website
On stocks i like to use the Wrinkle Paint, very durable, just takes about two weeks to cure out properly.
Its all fun tring to come up with new styles and designs.