{"product_id":"rock-river-arms-mid-length-a4-450-bushmaster-completed-upper-stainless-steel-450b0461","title":"Rock River Arms Mid-Length A4 .450 Bushmaster Completed Upper Stainless Steel 450B0461","description":"Rock River Arms Mid-Length A4 .450 Bushmaster Completed Upper\n\u003cp\u003eThe Rock River Arms Mid-Length A4 .450 Bushmaster Completed Upper is a precision-engineered, ready-to-run upper assembly built for hunters and shooters who demand performance and reliability. Chambered in the hard-hitting .450 Bushmaster cartridge, this upper features a 16-inch 416R stainless steel barrel with a 1:24 twist rate and cryogenic treatment for enhanced accuracy and extended barrel life. The forged A4 upper receiver is finished in a durable black anodize, while the RRA 13-inch Extended Lightweight Free Float Rail with M-LOK compatibility offers a versatile, low-profile platform for accessories. The low-profile mid-length gas block system provides smooth, reliable cycling, and the included RRA Operator Brake with 5\/8-32 threading effectively manages recoil. This complete upper ships with a Bolt Carrier Group, Charging Handle Assembly, and a 5-round magazine, making it a true out-of-the-box solution for any compatible AR-15 lower.\u003c\/p\u003e\n\n\u003ch3\u003eProduct Highlights\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHard-Hitting .450 Bushmaster Caliber:\u003c\/strong\u003e Designed for big-game hunting and serious range performance, delivering substantial knock-down power in an AR-platform package.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCryogenically Treated 416R Stainless Steel Barrel:\u003c\/strong\u003e The 16-inch barrel undergoes cryogenic treatment for improved wear resistance, extended service life, and consistent accuracy with a 1:24 twist rate.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRRA 13-Inch Lightweight Free Float Rail:\u003c\/strong\u003e The M-LOK compatible extended free float handguard reduces weight while providing ample real estate for bipods, lights, and other accessories.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRRA Operator Muzzle Brake:\u003c\/strong\u003e The 5\/8-32 threaded RRA Operator Brake effectively reduces felt recoil and muzzle rise for faster follow-up shots.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eComplete Ready-to-Install Assembly:\u003c\/strong\u003e Includes a Bolt Carrier Group, Charging Handle Assembly, and one 5-round magazine -- drop it on your compatible lower and go.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecs\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Rock River Arms\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number (MPN):\u003c\/strong\u003e 450B0461\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 842834124138\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCaliber:\u003c\/strong\u003e .450 Bushmaster\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUpper Receiver:\u003c\/strong\u003e Forged A4\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBarrel Length:\u003c\/strong\u003e 16 in\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBarrel Material:\u003c\/strong\u003e 416R Stainless Steel\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBarrel Twist Rate:\u003c\/strong\u003e 1:24\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBarrel Treatment:\u003c\/strong\u003e Cryogenically Treated\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall Length:\u003c\/strong\u003e 24 in\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGas System:\u003c\/strong\u003e Mid-Length\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGas Block:\u003c\/strong\u003e Low Profile, .936 in Journal Diameter\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMuzzle Device:\u003c\/strong\u003e RRA Operator Brake, 5\/8-32 Thread\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHandguard:\u003c\/strong\u003e RRA 13-Inch Extended Lightweight Free Float Rail\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHandguard Compatibility:\u003c\/strong\u003e M-LOK\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRail:\u003c\/strong\u003e Full Top Picatinny Rail\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFinish:\u003c\/strong\u003e Black Anodized\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 4.47 lb\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIncludes:\u003c\/strong\u003e Bolt Carrier Group, Charging Handle Assembly, One 5-Round Magazine\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eDisclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product's manufacturer.\u003c\/em\u003e\u003c\/p\u003e\n]]\u0026gt;","brand":"Rock River Arms","offers":[{"title":"Default Title","offer_id":44200135721082,"sku":"FLX-157967","price":732.98,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1679\/0365\/files\/297589836.png?v=1788406814","url":"https:\/\/tlooutdoors.com\/products\/rock-river-arms-mid-length-a4-450-bushmaster-completed-upper-stainless-steel-450b0461","provider":"TLO Outdoors","version":"1.0","type":"link"}