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RISE Armament Watchman XR 6mm ARC 18 Inch Complete Upper Receiver Assembly Black RA 6ARC CU BLK 18 UPC 850043415947
Product Description
The RISE Armament® Watchman XR 18" 6mm ARC Complete Upper Receiver Assembly (SKU: RA-6ARC-CU-BLK-18 / UPC: 850043415947) is a turnkey, match-grade long-range solution engineered to maximize the ballistic efficiency of Hornady’s 6mm ARC cartridge on the standard AR-15 platform. Designed for precision PRS gas-gun competition, predator control, and DMR tactical applications, this fully assembled upper receiver transforms standard lower receivers into flat-shooting precision instruments capable of extreme accuracy well beyond 1,000 yards.
At the mechanical core of this assembly is an 18-inch 416R stainless steel barrel precision-buttoned with a 1:7 twist rate to stabilize heavy, high-BC 103-grain to 108-grain match projectiles. The barrel is seated in a rigid 7075-T6 forged billet aluminum upper receiver coated in a durable MIL-A-8625 Type III Class 2 hardcoat anodize to shrug off field abrasion and environmental exposure. Cycling is driven by a factory-tuned black nitride bolt carrier group featuring an 8620 steel carrier, an individually MPI-inspected 9310 alloy steel bolt, and a properly torqued, staked gas key that delivers slick operation and exceptional resistance to carbon fouling.
Encasing the barrel assembly is a 15.25-inch lightweight free-float handguard featuring full-length top Picatinny rail space and ergonomic M-LOK mounting slots along the 3, 6, and 9 o'clock flats for bipods, tripods, and weapon-mounted illuminators. Paired with a rifle-length gas system that dramatically softens the recoil impulse and extends bolt unlock dwell time, the upper comes fully equipped with a RISE ambidextrous charging handle, ensuring lightning-fast manipulation from either shooting shoulder.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Drops directly onto any standard Mil-Spec AR-15 forged or billet lower receiver. CRITICAL: Requires dedicated 6mm ARC or 6.5 Grendel magazines for flawless feeding; standard 5.56 NATO/.223 magazines will induce double-feed and nose-dive jams. Note muzzle thread pitch is 1/2x28 UNEF-2A; ensure any aftermarket muzzle brake, compensator, or suppressor direct-thread mount features an aperture cleared for 6mm/.243 caliber bullets before torquing to 20-25 ft-lbs with a crush washer or shim kit.
- Ensure the host AR-15 lower receiver is visually and physically verified empty, magazine removed, and hammer rested in the forward uncocked position.
- Inspect the pre-installed RISE bolt carrier group and ambidextrous charging handle, verifying proper lubrication on all carrier bearing surfaces and cam pin raceways.
- Push out the front pivot and rear takedown pins on your host lower receiver, position the upper receiver front lug into the pivot pocket, and press the pivot pin fully closed.
- Hinge the upper receiver down onto the lower receiver deck and seat the rear takedown pin flush into its detent channel.
- Perform a comprehensive five-point dry-fire function check, confirm proper bolt lock-back on an empty 6mm ARC magazine, and verify muzzle alignment with a concentricity rod prior to live-fire range zeroing.
Key Features
- Match-Grade 416R Stainless Steel: 18-inch barrel with 1:7 twist rate delivers supreme stabilization for high-BC 6mm bullets in extreme long-range applications.
- Rifle-Length Gas System: Significantly reduces carrier velocity and felt recoil, yielding smooth cycling, minimal sight picture disruption, and extended brass life.
- Type III Hardcoat Anodized 7075-T6 Receiver: Premium forged billet receiver provides a robust, flex-free mounting base for heavy target optics.
- 15.25-Inch Free-Float M-LOK Handguard: Maximum barrel harmonics isolation with modular mounting points for match bipods, barrier stops, and night vision devices.
- Complete Factory BCG & Ambi Charging Handle: Outfitted with an MPI-tested 9310 black nitride bolt assembly and RISE ambi charging handle for out-of-the-box readiness.
Product Specifications
- Brand: RISE Armament®
- Model/Series: Watchman XR 6mm ARC Complete Upper Receiver
- MPN / SKU: RA-6ARC-CU-BLK-18 / RISERA-6ARC-CU-BLK-18
- UPC: 850043415947
- Platform Compatibility: Standard Mil-Spec AR-15 Lower Receivers
- Country of Origin: United States of America
