That stock doesn't appear to be Walnut, unless it's been bleached. Looks like a M2 style stock.
And by blowing this picture up and adding some light it looks as though there might be 2 letters markings about 1" down from the gas cylinder / piston opening.. Right down at the very bottom of the picture.
Eddie,
Did you look on the barrel area that the bayonet band is covering ?
A picture of the barrel just behind the front sight 'Might' help