I took my synthetic stock and filled it with expandable foam, after it set i cut of the excess and replaced the recoil pad and went out and shot it. now this is just my non scientific experiance but the felt recoil was noticably different. IMHO the expandable foam allowed the recoil to be distributed over the entire surface area of the recoil pad before transfering into my shoulder and thus giving more surface area to spread the load out onto. before i filled the stock the recoil is coming through the walls of the stock only and distributed around the outside perimeter of the recoil pad and results in a sharper felt recoil because the same load is concentrated over a smaller surface area. this is why i feel a synthetic hollow stock (and sometimes narrow too) tends to feel like it has more thump to it.
flame suit on, blast away.
