Take it off the stock and use the B & R Jig with an 8" or bigger bench mounted disc sander with a rigid disc running at least 1600 RPM. I have used a homemade clone of this jig for many years and it is the best one I have ever seen anywhere. You can cut a pad or a plate to a perfect fit off the stock with the stock lines correctly carried on to the pad. I grind almost to the line with 60 grit AO and cut the line away with 180 grit AO. This leaves a very smooth finish that you can polish by hand if you like.
http://www.brownells.com/.aspx/pid=9152/Product/RECOIL_PAD_FITTING_JIGOB
