Griffin Armament’s MK1 Upper offers premium features and reliability to each user and allows end users to configure their upper to fit their needs.

The Griffin HEDP Barrels provide High Endurance Dual Purpose functionality- offering high durability and precision accuracy. Nitride 416R stainless steel provides the highest possible hardness and longest throat life available with match grade bore dimensions and bore finish. HEDP barrel bores are hand lapped, ensuring batch to batch consistency and accuracy. TRUE-BORE concentric suppressor grade threads provide an optimized thread interface for your silencer regardless of brand or model. M4 feed ramps and chambers are polished prior to nitriding for smooth reliable feeding, chambering, and extraction. M4A1 contour diameter between the chamber and gas block for minimal POI shift with suppressors and maximum accuracy and durability while maintaining field weight.

Griffin Low-Pro RIGID rails are a slim, low profile, ultralight, yet rigid M-LOK rail. Design objectives of this rail were to provide a slim, ultralight rail, with increased rigidity over similar weight and profile current market options. A custom extrusion provides significant internal reinforcement to reduce flex when gripping the carbine firmly in the shoulder pocket. Understanding the importance of low light targeting, these reinforcements provide rigid mounting for IR laser aimers ensuring minimal POI shift when torque is applied to fore-grip type accessories, or when loads are applied to the rail (shooting off barricades, loaded bipods etc). Internal testing showed 70% less POI shift with laser aimers versus competing “slim rails”. Carefully positioned slots in the rail allow for rapid cooling when running the carbine fast while maintaining rigidity.

The Low-Pro RIGID rail features a lightweight 7075 T6 Aluminum barrel nut, which can be installed with any car stock wrench or by using the included Griffin Armorers Wrench. Included shims allow barrel nut timing and keep the rear section of the rail low profile and ergonomically pleasing for relaxed posture carry at static positions. The included 17-4 stainless steel anti rotation QD sling swivel sockets install through the rail using a standard QD sling swivel (not included) and into the nut, ensuring that the rail is kept as low-profile as possible. In the same way, flat socket head cap screws are used in keeping with the sleek design objectives. M-LOK slots at the 3, 6, and 9 o’clock positions allow for mounting of your favorite M-LOK accessories.

Features

• 416R SS barrel manufactured from stress relieved certified barrel steel
• Black nitrided for extended service life
• Magnetic particle inspected
• Button rifled
• 300 Blackout chamber
• Pistol gas system
• .750″ gas block journal
• M4A1 diameter for reduced POI shift / Increased Accuracy & Durability
• Air gauged and hand lapped bore
• Polished chamber and M4 feed ramps
• TRU-BORE suppressor quality threads
• Suppressor optimized gas ports