The Rock River LAR-BT3 X-1 is an AR-pattern semi-automatic rifle chambered in .308 Winchester with an 18-inch barrel and synthetic stock. It has a 30+1 round capacity and a black finish throughout. One vendor listing notes a 20-inch barrel variant with a Magpul Gen3 Precision Stock. 
 

Key Specifications 

• Brand: Rock River Arms 
• Model: LAR-BT3 X-1 
• Caliber: .308 Win 
• Action: Semi Auto 
• Capacity: 30+1 
• Barrel Length: 18 in 
• Color/Finish: Black 
   

Detailed Features 

• AR-pattern platform chambered in .308 Winchester 
• 18-inch barrel with black synthetic stock 
• 30+1 round capacity 
• Also available in a 20-inch barrel configuration with Magpul Gen3 Precision Stock per some listings

Owners of the Rock River LAR-BT3 X-1 generally appreciate the .308 Win AR-pattern format for its parts compatibility and familiar manual of arms. The 18-inch barrel length strikes a balance between muzzle velocity and handling for a full-power cartridge, and most owners report solid reliability out of the box.

The synthetic stock draws divided opinions. Some shooters find it adequate for a working rifle, while others swap it out fairly quickly in favor of a chassis or adjustable stock. The Magpul Gen3 Precision Stock variant appeals more to owners who want a precision-oriented setup from the start.

Rock River's pricing relative to competitors comes up often. Buyers who prioritize American manufacturing and a straightforward AR-10 platform tend to be satisfied. Those comparing spec-for-spec against other .308 AR builds sometimes feel the price point requires more justification.