The Kel-Tec RDB Defender in OD Green is a semi-automatic bullpup rifle chambered in 5.56 NATO / .223 Remington. The bullpup configuration keeps overall length to 27 inches while retaining a 16.1-inch barrel. This variant weighs approximately 6.4 pounds and uses a collapsible bullpup stock with a polymer receiver. 
 

Key Specifications 

• Model: RDB Defender 
• Caliber: 5.56 NATO / .223 Remington 
• Barrel Length: 16.1 inches 
• Capacity: 20+1 rounds 
• Overall Length: 27 inches 
• Weight: Approximately 6.4 pounds (102.4 ounces) 
• Action Type: Semi-Automatic 
• Stock Description: Collapsible Bullpup Stock 
• Twist Rate: 1:7 inches 
• Receiver Material: Polymer 
• Finish Color: OD Green 
   

Detailed Features 

 
The RDB's downward ejection system means the gun functions the same from either shoulder without brass deflection issues. AR-style magazine compatibility keeps ammunition and spare mags easy to source. The Picatinny rail on the receiver accepts standard optics without adapters. 
 
The adjustable stock allows some length-of-pull customization. A manual safety lever is on the receiver, accessible without shifting grip. At 6.4 lbs. the rifle is light enough for extended carry, though the balance feels noticeably different from a conventional rifle due to the rearward weight distribution. 
 
The 1:7 twist rate suits heavier projectiles in the 62-77 grain range. The OD Green finish is the only color distinction from the standard black Defender. 
 

Usage Notes 

 
Suitable for home defense, range training, and light hunting in states where 5.56 is legal for the application. Competitive shooters who want to explore bullpup handling will find the RDB an accessible option in the category. Left-handed shooters benefit more from this design than from most conventional semi-auto rifles.

The RDB Defender in OD Green generates discussion along the same lines as the standard black version, with the color occasionally drawing comments on its own.

Positive points that come up consistently:

• The bullpup layout draws real enthusiasm from owners who wanted a compact rifle without cutting barrel length. Most appreciate the 27-inch overall length.
• The downward ejection and ambidextrous controls get specific praise from left-handed shooters.
• Weight and portability are regularly mentioned as strengths.
• The adjustable gas system is noted positively by owners who run a variety of ammunition.

Critical points:

• Build quality concerns come up relative to comparable-priced traditional ARs. The polymer construction is lighter but feels less substantial to some users.
• Trigger feel is a frequent discussion point. The bullpup trigger linkage produces a longer, heavier pull than many AR triggers, and first-time bullpup shooters notice it immediately.
• Aftermarket support is thinner than for AR-pattern rifles, which limits customization options.
• Some owners report reliability issues at higher round counts or with certain ammunition, though experiences vary widely.