Well, crap. This is a reminder that I need to get off my butt and take some pictures to post for my how-to on measuring trigger pull for a standard rifle/shotgun frame. The write up is all done, but I can't take the pictures of myself doing the measuring and I spent all weekend working on the yard and such.
As was mentioned by C3 - You really need to start with knowing your measurement, because adding a recoil pad that will ease some of the impact from the recoil, will most likely add to the length of pull on the weapon.
Does your current weapon have a screw on style butt/recoil pad? It would probably have two screws, going from the back, directly into the stock. Removing the screws allows you to remove the butt plate / recoil pad.
If that is the case, then you can measure the size of your current model and know what you are shopping for. Almost every rifle has some sort of removable butt plate and/or recoil pad, but some do not and others are modeled right into the stock manufacturing.
As for recoil pads themselves. There are two that we specifically install on firearms in the shop.
makes a model called the Decelerator that is what I have on all my boltguns. It is very high density and works really well. This is a custom install, it needs to be ground to fit, so unless you have the tools, you might need some help. However, Pachmayr also makes several models that are cut to fit most common rifle and shotgun applications. This site is the first one I found with their whole selection, but find what you want and shop around. The internet is a wonderful place.
is another company turning out a fine recoil pad. They offer many different types, some grind to fit, some custom done for you and some basic applications. They have ( 3 ) in the H & R rating, made of different materials. Check them out and see what you think. As always, shop the 'net and find yourself the best prices.
Hope that helps!