CMMG Endeavor Mk3 20-Inch AR Rifle, 20-Round Magazine

Description

The CMMG Endeavor Mk3 is built for shooters who want to press the effective range of the AR-10 platform in .308 Winchester — think long-range target work, hunting at distance, or a general-purpose precision rifle that doesn’t require a dedicated bolt gun. The Mk3 receiver set follows the LR-308/DPMS Gen 1 high-pattern layout, which keeps it compatible with a wide ecosystem of aftermarket components.

The barrel is 416 stainless steel with a nitride finish, a pairing that gives you the corrosion resistance of stainless with a surface hardening that better withstands fouling and wear. A 20-inch tube gives the .308 cartridge enough dwell time to develop its full powder charge, translating into higher muzzle velocity and flatter trajectories than you’d get from a shorter gas system — relevant when you’re calling shots past 500 yards. The barrel is threaded 5/8×24, the standard pattern for .308, and ships with CMMG’s ZEROED muzzle brake already fitted, which reduces muzzle rise and lets you spot your own impacts.

CMMG’s Radial Delayed Blowback operating system differs from a conventional direct-impingement or piston setup: the bolt head uses radially cut locking lugs that cam outward into the barrel extension and delay bolt travel until chamber pressure drops to a safe level, which takes a meaningful amount of recoil impulse off the shooter’s shoulder. The free-float M-LOK handguard removes barrel contact points that could affect point of impact under sling tension or barrel heat. The CMMG Ripstock and ZEROED polymer grip are the factory furniture. Finish is Cerakote Armor Black throughout.