CA- The reciever is carbon fiber- and much of the upper. Of course the springs, BCG, bolt and barrel are steel, but the rest is mostly carbon. Little metal plate inset in the lower withh the stamped SN.
These DO take down a bit differently than a standard AR- you cannot pull the rear pin and "shotgun" the upper/lower. Pull both pins, lift the FRONT, and upper and lower pivot apart on a lug at the rear. DOES lock it up good and tight- no wiggle at all between upper/lower.