Probably the most effective recoil pads around are the Limbsaver polymer types.
Limbsaver makes one for Remington, which Remington calls the "R3", and uses on the Police guns and some other hard-kicking guns.
According to Remington, the Limbsaver-R3 reduces felt recoil by 30% over regular pads.
Most people who've tried one, report that buckshot or slugs feel like field loads.