I've gotten the pad sanded down so that the hard base is level with the butt stock wood, but the soft rubber portion "stands proud" above the base. I know that putting the stock in the freezer overnight will make the final sanding easier, but I read somewhere about using some sort of oil or wax for the final sanding/finish on the soft rubber portion of the pad. What oil or wax should I use and how? I'm using 1000 grit wet or dry sandpaper at this point. Thanks!