AK-47: Metal, ABS plastic. But the stock of the gun... It's kind of plasticy, but not that bad. I doubt it would break though. It's a nice gun.
M14: All metal insides/outside(such as bolt, sights, ect.). The body of the gun though is fiberglass body, or a rubber fiberglass body. It's like a grip fiberglass. VERY sturdy though.