I would use Brownells Gun-Kote. It comes in rattle cans or bulk that you spray on with an air pencil. You have to bake the gun in the oven, but it does not stink up the house.
Spraying on the Gun-Kote is another story. Have good ventilation and a mask when spraying. You will have the same tough finish you get on factory guns.
If you mess up the paint job, it can be removed with brake cleaner before baking. Once baked, the only way to get the finish off is to bead blast the part. You should have the part bead blasted with a fine grit for the best adhesion and looks before painting. I like using the air pencil with several light coats. You can get air pencils at harbor feight or a hobby shop for a low price, you don't have to buy the $100 ones.
Spray paint comes off too easy and scratches. The Gun-Kote cannot be removed by bore cleaners either.
www.brownells.com
Also, clean with brake cleaner before spraying and don't touch the metal with your hands. You want no oil on the part, it needs to be totally clean. It may cost a little more, but why not do it right.
I have done more than I can count for my customers and they all love the results. They don't come back because the finish has come off either.
John K