Hi Wilba,
I filled my stock with expanding foam (slowly and in stages) with the butt plate off. Allowed it to cure and trimmed. Defiantly deadened the noise, but lost interest in the military look and put the action back in to its original wood 'woodsman' stock. As others have said, be careful with this stuff on your hands and use sparingly as it expands a fair bit!!
Chris
Falcon Raptor (FN12) Lighthunter - Walnut FX Cutlas - EB XVI - HW35 'Karbine' - BSA Airsporter MK4 - Webley Mk III - Relum Tornado - FWB Sport 127 Deluxe - Crosman 1322 custom - Sussex Armoury Jackal - BSA Superstar - Logun Eagle (All .22) and HW80 in .25