Hal, Find some walnut close to your color and take a hand plane and shave off some curls long enough for your job. Put some good wood glue on them like Titebond waterproof(it will soak and soften them). Then just layer them to the stock like ply wood and clamp them in place. Fit the stock to the gun. This is one way to "grow" wood back that is gone. The layers look like the grain of the wood.