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Rock River Arms Completed Pistol Upper Receiver A4 .223/5.56mm 4.5 Inch Barrel 1-9 Twist 1/2-28 Thread Free-Float Handguard Vortex Flash Hider Black

Name: Rock River Arms Completed Pistol Upper Receiver A4 .223/5.56mm 4.5 Inch Barrel 1-9 Twist 1/2-28 Thread Free-Float Handguard Vortex Flash Hider Black
Brand: Rock River Arms
SKU: AR0369B
Price: 609.99 USD
Availability: OutOfStock

Rock River Arms Completed Pistol Upper Receiver A4 .223/5.56mm 4.5 Inch Barrel 1-9 Twist 1/2-28 Thread Free-Float Handguard Vortex Flash Hider Black - Upper Receiver for AR-15 - view 1

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Rock River Arms

Overview

The Rock River Arms Completed Pistol Upper Receiver is designed for the AR-15 platform and features a 4.5-inch barrel chambered in 5.56 NATO, providing a compact option for those seeking maneuverability. With a 1:9 twist rate, this upper receiver is optimized for stabilizing a range of bullet weights, making it versatile for various shooting applications. Its A4 receiver type and included free-float handguard enhance accuracy and allow for customization with accessories. This upper is commonly found in short-barreled builds or pistol configurations, perfect for close-quarters engagements.

Specifications

MPNAR0369B

Receiver TypeA4

Caliber5.56 NATO

Twist Rate1:9

ColorBlack

PlatformAR-15

Barrel Length4.5

AssemblyComplete

Thread Pitch1/2x28

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Rock River Arms Completed Pistol Upper Receiver A4 .223/5.56mm 4.5 Inch Barrel 1-9 Twist 1/2-28 Thread Free-Float Handguard Vortex Flash Hider Black

Available Merchants(1)

Prices checked Sep 28, 2026

Stock Alert

Optics Planet

Free shipping

Shipping Speed

Out of Stock

$610

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Build history on GunPartPicker

Builders have been adding the Rock River Arms Completed Pistol Upper Receiver A4 .223/5.56mm 4.5 Inch Barrel 1-9 Twist 1/2-28 Thread Free-Float Handguard Vortex Flash Hider Black to their builds on GunPartPicker since July 2026. All time, it ranks #457 of the 1,634 upper receivers builders have added.

It was out of stock everywhere we track for all of August 2026, and today the one retailer we track is out of stock. Listed prices start at $609.99 at Optics Planet for when it comes back.

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Updated Sep 29, 2026 · from real builds on GunPartPicker · Prices checked Sep 28, 2026 · refreshed daily across 35 retailers