The Kel-Tec RDB-S is a semi-automatic bullpup rifle chambered in .223 Rem / 5.56 NATO with a 16.1-inch barrel. Its bullpup layout puts the action behind the trigger, resulting in a 26.1-inch overall length with a full-length barrel. It weighs 5 lbs 14 oz, has a 20+1 capacity, and is finished in OD Green polymer with a salt bath nitride barrel. 
 

Key Specifications 

• Model: RDB-S 
• Caliber: .223 Rem / 5.56 NATO 
• Barrel Length: 16.1 inches 
• Overall Length: 26.1 inches 
• Capacity: 20+1 rounds 
• Weight: 5 lbs 14 oz (5.14 lbs) 
• Finish: Green Polymer with Salt Bath Nitride barrel finish 
• Safety: Manual Thumb Safety 
• Sights: Adjustable front and rear sights with optic-ready rail 
   

Features 

The bullpup configuration keeps the overall length at 26.1 inches while running a 16.1-inch barrel, which is more compact than a traditional rifle with the same barrel. Ambidextrous controls are built in. The RDB-S accepts standard AR-15 magazines, including the included 20-rounder. The optic-ready top rail takes any standard mount. The salt bath nitride barrel finish resists corrosion. Adjustable folding iron sights come installed.

The Kel-Tec RDB-S draws a predictable mix of enthusiasm about the format and skepticism about early-production reliability.

The bullpup layout is the main attraction. The compact overall length with a full-length barrel appeals to shooters who want maneuverability without going to a short-barrel configuration. At under 27 inches with a 16.1-inch barrel it's noticeably shorter than a standard AR-15.

Ambidextrous controls and compatibility with standard AR-15 magazines are consistently cited as practical advantages.

Reliability concerns show up regularly in discussions, particularly around certain ammunition types and rapid-fire strings. Some early adopters reported fitment and function issues out of the box, and this has tempered overall enthusiasm.

Adaptation to the bullpup control layout takes time for shooters accustomed to conventional rifles. Magazine changes and charging handle placement require different muscle memory.

Aftermarket accessory options are more limited compared to established platforms like the AR-15, which matters for owners who want to customize extensively.

Overall sentiment is positive for the concept but split on execution, with opinions varying based on individual production runs and experiences.