All our uppers are carefully assembled and tested and ready to go out of the box. Every component is chosen to ensure a high quality upper is produced. Every upper is custom built to order and we go the extra mile to ensure the finished product is to your specifications. This 308 Win upper starts with a Gibbz Arms G10 AR-10 308 Non Reciprocating Side Charging Billet Aluminum receiver, mated to a Ballistic Advantage 20 inch 308 Win, Rifle Length Gas System, 1:10 Twist, Heavy Profile, QPQ Nitride/Melonite treated barrel. The Gibbz Arms G10 receiver is a DPMS Low Spec Gen 1 Style receiver and is a proprietary patented receiver that has a non reciprocating side charging handle - handle stays forward during cycling. Side handle is on the opposite side of ejection port allowing the shooter to quickly charge or recharge the weapon without taking finger off the trigger and eye off the scope. Ballistic Advantage is one of the best barrel manufacturers in the industry and they produce high quality, accurate barrels. The Bowden Rail is a DPMS LOW SPEC, free floated system, M-LOK slots on all three sides, full length picatinny rail at the top, lightweight handguard. Barrel Nut is made out of solid steel to ensure a solid mounting system to withstand the recoil of the AR-10 system. Bolt Carrier Group is OPTIONAL. We offer a 308 Win BCG from WL Armory, Full Auto Profile, Properly Staked Gas Key, MP Tested, 8620 Carrier, 9310 Bolt, Nitride Treated. Comes with a Black Competition Muzzle Brake. This is an enhanced version of the popular style muzzle brakes. The baffles and ports are milled larger to drive pressure up and to keep the muzzle down more effectively. Comes with an Adjustable Gas Block. Perfect if you are using a suppressor or just want to fine tune your system. SPECIFICATIONS UPPER RECEIVER: Gibbz Arms G10 308 Non Reciprocating Side Charging Receiver with Gen 2 Handle (Gibbz Cam Pin Included) BARREL: 20 inch, 308 Win Caliber, 4150 Chrome Moly Vanadium Steel, 1:10 Twist, Heavy Profile, QPQ Nitride/Melonite Treated - made by Ballistic Advantage HANDGUARD: 15 inch AR-10 M-LOK Free Floated, Machined out of 6061 T6 Aluminum - made by Bowden Tactical GAS SYSTEM: Rifle Length, Direct Impingement, Stainless Steel Tube GAS BLOCK: Adjustable Low Profile Gas Block, Machined out of 4140 Steel MUZZLE DEVICE: Black Competition Muzzle Brake with Crush Washer 100% MADE IN THE USA OPTIONAL: ADD a WL Armory 308 Win Nitride M16 Profile BCG NOTE on COMPATIBILITY: Upper will fit most DPMS SPEC Gen 1 lower receivers on the market (NOTE: some filing may be required on the lugs of the upper or lug area of the lower on some brands) mainly Aero Precision, New Frontier Armory, Gibbz Arms, Noreen and etc. YES upper WILL work with a PSA PA-10 Lower but upper receiver sits a little higher than the lower receiver. Upper is NOT compatible with Anderson Mfg's AM-10 308 Lower. Upper is NOT compatible with Armalite's AR-10 type lowers. This is just a guide and not a complete list of compatible and incompatible lowers.