Mike, you sent me several O-rings when I bought the rifles from you. There are 2 different #113 O-rings, some are red and some are black. I'm guessing that the red ones are the silicone valve O-rings and the black ones are the Viton cap O-rings. Is this correct? I could replace the valve O-ring, but I think it is fine because when I cycled the rifle (fired it) the gas leakage slowed. It seems like it is/was the seal.