The Kel-Tec RDB is a semi-automatic bullpup rifle chambered in 5.56x45mm NATO / .223 Remington. This variant ships with a 20.5-inch barrel, giving it an overall length of 30.4 inches and a weight of 7.2 lbs. One 20-round magazine is included. The optic-ready rail accepts standard accessories without adapters. 
 

Key Specifications 

• SKU: 179400942 
• UPC: 640832002720 
• Caliber: 5.56x45mm NATO / .223 Remington 
• Action: Semi-Auto 
• Capacity: 20 rounds (1 magazine included) 
• Barrel Length: 20.5 inches 
• Weight: 7.2 lbs. 
• Finish: Black synthetic stock 
• Overall Length: 30.4 inches 
• Twist Rate: 1:7" 
• Design: Bullpup configuration 
• Sights: Optic ready rail 
   

Detailed Features 

 
The longer 20.5-inch barrel extracts a bit more velocity from 5.56 loads than the 16.1-inch Defender variant while keeping overall length nearly 10 inches shorter than a traditional 20.5-inch-barreled rifle would. Downward case ejection makes the RDB genuinely ambidextrous. The trigger uses the standard bullpup linkage, which will feel different from an AR trigger and benefits from practice time. 
 
AR-style magazine compatibility is standard. A manual safety is on the receiver. The black synthetic stock holds up well to weather and rough handling. At 7.2 lbs. this is slightly heavier than the shorter Defender version due to the longer barrel. 
 

Usage Notes 

 
The longer barrel makes this configuration a better fit for range shooting and hunting applications than strictly close-quarters work. The compact length still has practical storage and transport advantages over a conventionally configured 20.5-inch rifle. Owners who shoot a mix of target, varmint, and training work will find the balance between velocity and handling practical.

The Kel-Tec RDB in the longer 20.5-inch barrel configuration draws similar reactions to the Defender, with some discussion specific to the barrel length tradeoff.

Common discussion points:

1. The bullpup compactness advantage is slightly reduced with the longer barrel, but the gun is still significantly shorter than a conventional 20-inch-barrel rifle. Most owners who bought the longer barrel chose it specifically for the velocity improvement.
2. Versatility across target shooting, hunting, and home defense use is frequently cited as a selling point.
3. Optic-ready configuration draws positive comments from owners who planned to run a red dot or LPVO from day one.
4. Reliability and feeding are generally reported as adequate for casual use, with some owners noting occasional issues with certain ammunition or at higher round counts.
5. Build quality discussions are similar to the Defender line: the polymer construction is lighter but divides opinion on perceived durability versus steel and aluminum alternatives.
6. Price is seen as competitive within the bullpup category, which tends to command a premium over comparable conventional designs.
7. Aftermarket accessories are more limited than for the AR platform, which is a real-world consideration for owners who want to customize extensively.