The SR-556 offers Ruger's legendary rugged reliability, redefining the AR platform with piston driven performance. The piston driven SR-556 runs cleaner, cooler, and is easier to maintain than gas driven rifles, offering significantly improved reliability.

The patent pending two-stage piston driven operating system in the Ruger SR-556 provides a smooth power delivery stroke to the action and vents combustion residue out of the bottom of the gas block. The four-position adjustable gas regulator allows the operator to tune the rifle to specific ammunition and rifle conditions, minimizing recoil and maximizing reliability and long-term endurance. Reliability is further enhanced by a one-piece bolt carrier with an integral transfer key.

Designed for long-lasting accuracy, the heavy contour, 16-1/8" chrome lined barrel is cold hammer forged from Mil-Spec 41V45 Chrome-Moly-Vanadium Steel. The barrel has a 1:9 twist rate and is capped with an AC-556 flash suppressor. Chambered in 5.56mm NATO, the Ruger SR-556 also fires .223 Rem. ammunition.

A one-piece, ten-inch Troy Industries Quad Rail Handguard provides ample room for mounting sights, optics and accessories. Made exclusively for Ruger, this SR-556-specific handguard is pinned to the upper receiver and provides a rigid mount for the piston driven transfer rod.

The SR-556 is equipped with Troy Industries Folding BattleSights™. These rugged, high-quality sights co-witness with Mil-Spec optics, and are easily removed or replaced. The sights can be folded down with the push of a button, or quickly flipped up with your thumbs. The windage adjustable rear sight includes an instantly converted short and long range aperture, and the protected front sight is elevation adjustable.

The Ruger SR-556 is equipped with a six-position telescoping M4-style buttstock that houses a Mil-Spec buffer and spring. A Hogue® Monogrip® pistol grip and three Troy Industries Rail Covers provide a comfortable ergonomic hold when carrying or shooting.

Durability and performance of the SR-556 is enhanced with the use of high-performance finishes: The barrel and gas block are chrome lined, while the bolt, bolt carrier, and extractor are chrome plated. The piston driven transfer rod is electroless nickel/Teflon coated. The flash hider and the exterior of the barrel, gas block, and regulator are manganese phosphate coated. All aluminum parts are Mil-Spec hard coat anodized.

The SR-556 is supplied with three, thirty-round Magpul PMAG™ magazines. These lightweight magazines feature a storage/dust cover, a stainless steel spring, and a self-lubricating, anti-tilt follower.

The flat top upper receiver and barrel assembly is specific to the Ruger SR-556. The standard lower receiver is built with Mil-Spec components, including a single stage trigger. The lower receiver is compatible with AR-style magazines, grips, buttstocks, and fire control components.

The 7 lb., 15 oz. (without magazine) Ruger SR-556 autoloading rifle is shipped in a padded carry case that features the Ruger logo, hook-and-loop fasteners to stabilize the rifle within the case, and internal magazine pockets.