I want to closely match the matte dark brown that the USGI synthetic stocks came in originally. I just bought 3 synthetics from Fred's, and want to cover the abrasions, dings and scuffs.  

Now to let the cat out of the bag.....I'm putting these on the demil'd M-14's my squadron has for ceremonies. The color guard has broken two nice wood stocks so far (one of which I replaced with a synthetic from my closet already).  My Sergeant Major is tired of them breaking them, can't get supply to replace them easily or quickly enough, so in a bit of horse trading, he wants synthetic and is letting me have the 3 other good wood stocks in exchange. I already grabbed the hardware from the two broken stocks....

You might checkout this--- Krylon Ruddy Brown Primer - RTA9204. Or some of the other red/brown automotive primers...