The original M40's had Composite stocks as designed by the Marine Sniper School instructors on Hill 55. You would be looking for the original Model 70's That were requisitioned by the instructors from the on base hunting lodges. Just a heads up there. But, if you have to make your own, what you'll need to do is to get a block of wood, slightly wider, taller, and longer than the maximum measurements of the stock you want to make, cut out the general shape on a bandsaw, then sand/file to the exact shape. After you have that done, you need to mill out the forestock for the action/barrel mounts of your gun.