blinddog,
I used natural sea sponge. It had kind of a hollow tip to it, once torn off from the main piece.
I sprayed Rustoleum Flat Espresso color into a paper plate & dipped the sponge in it & "stamped" the rifle....after I had appied the basecoat of sondstone, and light tan for the "belly" of the rifle.
The spots, or accent colors are the last thing I do before adding a good coat of matte clearcoat. (Also Rustoleum).
I did a thread here with pics & a tutorial on my M-4 that I camoed. It was the same proceedure for this one, only I used the spots instead of camo colors.
Hope that helps some.
Barry