Rattle Can: Kylon/Rustoleum
Base coat usually ends up being DupliColor pick-up-truck bed liner.
Airbrush: Folk Art Outdoor/ Createx / Model Master Acryl
I favor Model Master the most due to small size of container.
Action/Barrel/Scope: I don't use the rattle can for this but they will work fine.
I use any of the above mentioned paints but lean toward Kustom Kolors out of Eugene OR. They come mixed for the airbrush and the color selection is pretty good. Also with some basic color mixing skills just about any color you wish may be constructed.
After painting the clear coat is important for long life. I've learned that clear coating is not as magical as some say. Plus its pretty much bomb proof.
Also, the local body shop would most probably do the clear coat for a very reasonable. I've found that several body shops would rather "play" with a gun stock than "work" on an auto body.
The tupperware stocks are an inexpensive thing to test on also an old wood stock that has no value would be good but I've not come across a wood stock of any sort that has no value. Thus an orbital sander comes in handy around here;)
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!