Take your AR-15 platform to the next level with this 6mm ARC 18 Complete Upper Receiver built for shooters who demand precision reliability and extended range performance. Designed around an 18-inch 416R stainless steel barrel with a 1:7.5 twist rate this upper provides excellent stabilization across the range of 6mm ARC projectile weights delivering outstanding accuracy for long-range shooting and hunting applications. – The free-float M-Lok handguard offers a lightweight and rigid platform that enhances accuracy while allowing shooters to easily mount lights bipods and other accessories. A nitride-finished bolt carrier group ensures smooth cycling and long-term durability under demanding use. – Built to Mil-Spec standards this complete upper receiver includes a charging handle and bolt carrier group making it ready to install on any Mil-Spec AR-15 lower receiver. Whether you’re building a precision rifle a hunting setup or a versatile AR platform this 6mm ARC upper provides the performance needed to stretch your rifles capabilities. – Caliber: 6mm ARC – Barrel Profile: HBAR – Muzzle Thread: 5/8X24 – Twist Rate: 1-7.5 – Gas System: Rifle – Material: 416R Stainless – Handguard Length: 18 in.