Stag 15 Tactical Rifles are chambered in 5.56 NATO and built around a 16" barrel with a 1/7 twist rate. These rifles have an A2 Flash Hider to reduce muzzle flash and a mid-length gas system, that is combined with a low-profile gas block, which provides reliability under any condition.The free-floating Stag 13.5" M-LOK Handguard features a slim, lightweight profile that offers increased ergonomics, maximum airflow, and modularity while continuing to provide the utmost strength and durability. The handguard provides an uninterrupted picatinny rail along the top which allows room for sights, optics and accessories the shooter may require. The Quad option on the handguard adds picatinny sections as part of the handguard on the muzzle end.This upper half does not include a BCG or Charging Handle.Action: Semi-Auto Direct ImpingementCaliber: 5.56 NATO | .223Twist Rate: 1/7 Button RifledMuzzle Device: A2 Flash HiderBarrel: 16", 4150 Steel, Government Profile, Phosphate Coated with Chrome LiningHandguard: Stag 15 13.5" M-LOK SL w/QDReceiver Material: Forged and Mil-Spec 7075 T6 Aluminum with Type 3 Hard Coat AnodizingBolt Carrier: NoneGas System: Mid-Length with Low Profile Gas BlockCharging Handle: NoneSKU: STAG15110121*Product images are for illustrative purposes only and may differ from the actual product.