You mentioned having an airbrush.
If you can spray cheap enamel and get a good finish, you can spray duracoat. Set 'er up about 40lbs and let it eat--don't try and "thin" it, just add the catalyst and go. It sprays like any other paint.
The big key is in the PREP.
I always blast the parts in the sandblaster before I spray. I will parkerize all the small parts I can (my tank is only 18", so that restricts most barrels!). Duracoat will adhere to a smooth surface, but likes a rougher surface (like most other coatings) to get a good "tooth."
Next step...DEGREASe...then do it again, just in case.
I start with something simple, like "Simple Green" for the parts cleaner. After than I like to heat the parts with a heat-gun, just enough to open up the pores of the metal just in case any oil is trapped. Then I'll wipe it down one last time with acetone.
Now, spray away.
Let it sit a few hours before handling it...and like I mentioned before, let it sit at least a week or two before assembly. It's designed to cure SLOWLY to stay somewhat pliable. This is why duracoat excels--it's not hard and brittle like most other firearm "paints."
It'll suck up dings and scuffs, rather than chip and flake like a lot of other finishes.
You can buy the complete kit to spray duracoat for ~$50, but it comes with compressed air in a can and a cheap single-action airbrush.
The tru-strip degreaser in the kit is nice, but a warm acetone bath won't leave any residue and works just as well (cheaper).
As mentioned, avoid reducer.
So all you're left with is the duracoat and hardener--which can be had for $16 per 4oz. That's enough to do two typical rifles (or three complete handguns, from my experience).
So if you already have the room, the airbrush, and some basic tools, the coating itself + degreaser is going to run you under $20 each if you coat two rifles.
Most "pro" finishers are asking ~$150-200 to completely do a typical rifle for you.
