Those synthetic stocks will have a much longer life than those old red, orange, black and brown recoil pads. Those old pads were made of natural rubber, and contained volatile plasticizes, when a two stage injection molding incorporates a "rubber" over molding, the material is not "rubber" but a two part urethane; this is the same stuff that they use to bond a steel frame to glass when making sunroof glass panels, shoe soles, foam in car seats; padding in dash boards, mud-flaps, automotive floor mats etc.; extremely resilient and chemical and heat resistant.