If you do not have a recoil pad jig and disc sander, you can do it like this...
Mount it on the stock and scribe around the stock on the back of the pad with a razor blade or other sharp implement. Then take it back off. In my early days, before having the "proper" equiptment; I used an angle grinder mounted with a 180 grit flap disk. Get some chalk filings into the scribed line so that you can see it better and then mount it in a vice and do one side at a time. Slowly and carefully grind it down to meet the line. This takes so finess, but it will work. And it prevents from damaging the stock.
