The Rock River Arms Fred Eichler Series AR-15 is chambered in 5.56 NATO / .223 Wylde with a 16-inch cryogenically treated barrel and a 1:8 twist rate. At 7.6 lbs. and 36 inches overall, it's a full-size AR-pattern rifle in a Flat Dark Earth / Black finish. 
 

Key Specifications 

• Model: Fred Eichler Series 
• Caliber: 5.56 NATO / .223 Wylde 
• Barrel Length: 16 inches (Cryogenically treated with a 1:8 twist) 
• Capacity: 20 rounds 
• Weight: 7.6 lbs 
• Overall Length: 36 inches 
• Finish Color: Flat Dark Earth / Black 
   

Features 

• Cryogenic barrel treatment: Reduces stress in the barrel steel and can improve dimensional consistency over the barrel's service life, contributing to more stable accuracy as round count builds. 
• 1/2x28 TPI threaded muzzle with RRA tuned ported muzzle brake: Accepts suppressors or compensators without an adapter. The muzzle brake reduces felt recoil and muzzle rise during follow-up shots. 
• Forged aluminum receivers: Both upper and lower are forged rather than billet-machined, which is the mil-spec standard and generally tougher under stress. 
• RRA Chrome Two Stage trigger: The non-reflective trigger shoe has a smooth first-stage take-up and a clean second-stage break, which improves shot-to-shot consistency compared to a single-stage mil-spec trigger. 
• Full-length top rail and free-float handguard: The free-float design means the handguard has no contact with the barrel, which eliminates pressure changes from grip or bipod attachment that can shift point of impact. The full-length top rail accommodates optics, lights, or other accessories.

The Rock River Arms Fred Eichler AR-15 in 5.56 NATO with 16-inch barrel gets solid reviews, with build quality and reliability coming up consistently.

Rock River's reputation for quality construction is part of the reason people feel confident buying this platform, and owner feedback generally confirms that the rifle performs to expectation out of the box. Accuracy and grouping consistency get positive mentions, and recoil is described as manageable — which is expected from a gas-operated 5.56 AR at this weight. The FDE/black color combination and overall aesthetics earn positive comments. The AR-15 platform's accessory ecosystem means owners frequently mention customizing with optics, grips, and other parts.

The main criticism is weight — at 7.6 lbs., some users find it heavier than comparable options in its class. A few mention wanting to swap or upgrade stock components for personal preference, which is fairly typical of AR-platform buyers who often have strong opinions on triggers and handguards.