Barrel: 10.5" chrome moly steel barrel. Chambered in 9mm, (9x19), with a 1/10 twist. The barrel is nitride treated for durability and finished off with a PSA 9" Lightweight Hex Full Picatinny M-Lok Free Float Rail, and a bird cage style A2 flash hider. Upper: Billet 6061-T6 Slick side AR upper is hard coat anodized black for durability. These upper receivers are made for us right here in the USA. Bolt Carrier Group: Gen 4 Hybrid 9mm BCG. Nitride-treated 8620 steel bolt, with an enhanced firing pin and external 5.56 style extractor. The bolt carrier group is compatible with most aftermarket fire control groups. Lower: Forged 7075 T6 aluminum and then hard coat anodized, these lowers are purpose-built to accept 9mm GlockA(R)-style magazines. Designed to work with PSA's new 9mm Hybrid uppers. The lower is assembled with a Palmetto State Armory MOE EPT Shockwave lower build kit with a Magpul Grip, KAK Industries shockwave buffer tube, and KAK Shockwave Blade. Does not include last round bolt hold open feature. *PSA Can't Guarantee Function With EndoMag 9mm Magazines