Rock River Arms Completed Upper Receiver Operator ETR .308/7.62x51mm 16 Inch Barrel 1-10 Twist Mid-Length Profile 5/8-24 Threat Free-Float Handguard
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Rock River Arms
Overview
The Rock River Arms Completed Upper Receiver is designed for the AR-10 platform and features a 16-inch barrel chambered in .308 Win. With its mid-length gas system, this upper provides a smoother cycling experience and reduced recoil, while the 1:10 twist rate ensures stability for a range of bullet weights. Builders often incorporate this upper into precision-oriented builds where reliability and accuracy are essential, making it a solid choice for varied shooting applications.
Specifications
Rock River Arms Completed Upper Receiver Operator ETR .308/7.62x51mm 16 Inch Barrel 1-10 Twist Mid-Length Profile 5/8-24 Threat Free-Float Handguard
Build history on GunPartPicker
Builders on GunPartPicker first added the Rock River Arms Completed Upper Receiver Operator ETR .308/7.62x51mm 16 Inch Barrel 1-10 Twist Mid-Length Profile 5/8-24 Threat Free-Float Handguard to a build in April 2026.
Availability is good: it was in stock at one retailer or another nearly every day in August 2026, but today the one retailer we track is out of stock. The best price drifted down from $769.99 to $749.99 over August 2026 without a real sale. Listed prices start at $749.99 at Optics Planet for when it comes back.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 35 retailers
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