I think aluminum. Cadmium is a toxic metal, and not suitable for machine parts, I think. From everything I've read, the P22 is OK if you run ONLY CCI thru it. Standard velocity, I think. I used to have one, and my buddy currently does. I LOVE the looks, feel & operation of this gun. Admittedly, I sold mine for lack of functioning, but I never gave it the chance, or was aware of the CCI ammo thing, ect.