I wouldn't rule out factory based on just the checkering. For one thing, at least in the pictures, the finish in the finger notch looks to match and blend in with the rest of the stock too well to be touched up. For another, if this were available as an option I think it unlikely that Browning would have had 2 totally different checkering patterns worked out just to accomodate a seldom ordered option that could be handled easily by letting the pattern just run out.

Roger