A lot depends on the material the stock is made from. The overmoulded type stocls are hard to get mearly anything to stick to. Anything called 'composite' or fiberglass or carbon fiber reinforced can use epoxy to build up with. You may well be better off gluing on a wood block, then shaping and covering with a neoprene material as sold by Brownells. There are also kits available, usually for combs on shotguns, of just the peel and stick neoprene material in various thicknesses. I've not used those kits but have used some of the neoprene wundheymer swells from Brownells with great satisfaction.
