One of the most tested and proven weapons systems in the world achieves ultimate refinement with the introduction of the SIG516 rifle. With its Nitride-treated, military grade barrel and adjustable, four-position gas regulator, the SIG516 incorporates all of the most desirable mechanical improvements. Add to these a free-floating forend, and you have the most advanced, versatile AR-based rifle available. M1913 Picatinny flat top upper receiver. Flip-up iron sights. The 516 Patrol features a hammer-forged 16” barrel that provides superior quality and unsurpassed accuracy. The B5 Systems Bravo SOPMOD stock is comfortable and functional with a cheek weld, a one-piece anti-rotational QD swivel mount, a no-slip cushioned buttpad, and an improved suregrip stock latch. The Patrol's quad rail handguard allows users to add a full range of accessories and lock them into place with confidence.