Proof Research AR-Style Barrel .308 Win 20" 1:10 Twist Carbon Fiber Wrapped Sendero - 5/8x24 Threaded

The Proof Research 100981 is a .308 Winchester AR-platform drop-in barrel built around a 20" carbon-fiber-wrapped stainless steel blank, designed as a direct-fit upgrade for Sig-pattern AR-10 / AR-308 rifles. The heavy Sendero contour provides the added barrel mass prized for hunting and precision applications, while the carbon-fiber wrap drops carry weight and accelerates cooling compared to a traditional all-steel blank.

Proof Research manufactures every barrel using single-point cut rifling, with each blank lead lapped and inspected at multiple quality-control stations. This 100981 configuration uses a 5-groove bore with a 1:10 twist rate that stabilizes the standard spread of .308 Win bullet weights, and the muzzle is cut 5/8"-24 for industry-standard muzzle devices and accessories.

Installation is straightforward, with a 2.5" breech length and a 1.20" shank diameter providing a secure, accurate fit in compatible upper receivers. The Sendero profile's added mass resists barrel whip and point-of-impact shift during sustained strings of fire, while the carbon-fiber-wrapped construction keeps the overall package manageable on an AR-10 platform.

Whether you are upgrading an existing Sig-pattern AR-10 build or assembling a precision .308 Win rifle from a complete upper, the Proof Research 100981 delivers the accuracy, weight savings, and durability of carbon-fiber-wrapped barrel technology in a turn-key drop-in package.