Faxon Firearms Sentinel, Semi-automatic Rifle, AR, 8.6 Blackout, 16 Barrel, 3 Port Muzzle Break, Carbine Length Gas System, Anodized Finish, Black, G3 Aluminum Streamline M-LOK Handguard, B5 Precision Collapsible Stock, B5 Pistol Grip, 1 Magazine, 20 Rounds FX8616 The Sentinel 8.6 BLK, part of Faxon's Summit Line of firearms, boasts a billet aluminum receiver set, G3 Aluminum Streamline M-LOK Handguard, 8.6 BLK MuzzLok Muzzle Device, and the impressive 1:3 twist Modified Big Gunner Profile Barrel.