The Rock River Arms RUK-9BT is a 9mm AR-15 pattern pistol with a 4.5-inch barrel and a 17-round capacity. It ships with an SBA3 brace, flip-up sights, and a 2-stage trigger. The finish is blue/black. 
 

Key Specifications 

• Brand: Rock River Arms 
• Model: RUK-9BT 
• Caliber: 9mm 
• Action: Semi Auto 
• Capacity: 17 rounds 
• Barrel Length: 4.5 inches 
   

Detailed Features 

• 4.5-inch barrel in an AR-15 pattern 9mm pistol configuration 
• Ships with SBA3 brace 
• Flip-up sights included 
• 2-stage trigger 
• 17-round magazine capacity

Owners of the Rock River Arms RUK-9BT appreciate the 2-stage trigger as a notable differentiator in the 9mm AR pistol segment. Rock River Arms triggers have a reputation for a cleaner break compared to mil-spec drop-ins, and buyers who prioritize the trigger often call it out as the reason they chose the RUK-9BT over competing builds.

The SBA3 brace inclusion is well-received for buyers who want a ready-to-run pistol without additional purchases. Some owners note the 4.5-inch barrel keeps the overall package compact, though they acknowledge the tradeoff in velocity compared to longer-barreled 9mm carbines.

Build quality feedback is generally positive, with the blue/black finish drawing favorable comments for appearance. A recurring criticism is that the proprietary magazine compatibility can limit options depending on which 9mm magazines the buyer already owns, and that aftermarket support is narrower than for some competing 9mm AR platforms.