The Sig 556 features the same high performance two position adjustable gaspiston operating rod system engineered by Sig's sister company Swiss Armsand marries it to a trigger housing that not only cuts the rifle's weightby a pound but is designed to accept standard AR magazines. The Picatinnyrail equipped receiver is made of high strength carbon steel with a durablewear resistant Nitron X rifle finish. The rifle comes equipped with asmooth two stage trigger. A 30 round magazine is supplied with each rifle.#52652 is supplied with three 30 round clear magazines, a side foldingstock, bush green barrel and stock finish and 16" carbine barrel.