It is spray paint (Rustoleum) with a clear matte finish.
Here's what I did:
I first removed anything that I did not want to be painted - swivel studs, recoil pad, scope, bipod rail, bolt. Then I wiped down the stock and barreled action with acetone. I then taped the parts of the action that I did not want to be painted (bolt release, trigger group, and tang/safety). I also taped the part of the picatinny rail that the rings make contact with. I then put the barreled action back in the stock and hung it with a piece of rope through the rear swivel stud hole.
Next the first coat of paint went on. In this case a satin white.
Once that coat was dry, I wrapped rope around the whole thing with random spacing.
With the rope in place, I applied the next coat of paint (black). This leaves the white only visible under the rope.
After that coat was dry, I wrapped more rope around before applying more paint.
I did three more coats with gray, tan, and a sage green. These coats were done lightly to allow some of each color to show.
When once again dry, I removed both pieces of rope. I then spritzed the whole thing with brown spray paint.
The last painting step was two coats of Rustoleum Matte Clear. After that was dry, everything went back together... finished product.