Rough finish it on a vertical belt sander carefull to allow for the toe angle of the stock.Then install on butt.Wrap one layer of fibreglass tape around the stock where you don't want to marr the finish up to the edge of the pad.Then finish the job with a hand sander to the conture of the stock.A Black+ Decker type hand sander[mouse ]works best.Use coarse to start with then finish with med to fine grit.Remove tape and there you go.Harold P.S. wear a face mask when sanding rubber or you'll get the dust in your lungs!