I used the Gunkote from Brownells in black and olive drab and neither really worked as good as I thought they should. I bought the spray cans. Before spraying, I beadblasted the blades and then cleaned with acetone prior to spraying. It was extremely runny....you had to mist each coat very lightly to prevent runs. I then cooked it in the oven and the black did ok...the olive drab just pealed off after awhile (a week or so).
I consulted my gunsmith buddy who uses it on some of his rifles and he told me to "not ever buy it in the little spray cans from Brownells....it is a different formula than what most folks spray." What you want is the cans of the paint that you run through your spray gun....you know...quarts, gallons of the liquid....it holds better and is more resistant to scratching. I have a few of his rifles made up this way and after a few seasons hunting with them...he must be onto something there, as they wear like iron.