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RDB
RDB
	Kel-Tec RDB-17 with an angled grip, flip up Iron Sights, and Trijicon MRO
Type	Semi-automatic rifle
Place of origin	United States
Production history
Designer	George Kellgren
Designed	2015[citation needed]
Manufacturer	Kel-Tec
Produced	2015[citation needed]–present
Variants	RDB, RDB-C
Specifications
Mass	6.7 lb (3.0 kg) (RDB-17) ; 7.1 lb (3.2 kg) (RDB-20)
Length	27.3 in (693 mm)
Barrel length	17.2 in (437 mm) (RDB-17) ; 20 in (520 mm) (RDB-20); 17.4 in (440 mm) (M43)
Cartridge	5.56×45mm NATO
Caliber	5.56
Action	Gas-operated, rotating bolt
Rate of fire	Semi-automatic
Sights	None

The Kel-Tec RDB (Rifle, Downward-ejection, Bullpup) is a bullpup carbine offered in 5.56×45mm NATO semi-automatic rifle, manufactured by Kel-Tec Industries of Florida. It uses a rotary bolt with a spring loaded ejector and an extractor facing down, ejecting spent shell casings downward, allowing easy ambidextrous use.

Design

The RDB was designed to be modular, and is broken down into four Assembly Groups, held together with HK style push-pins:

The Barrel Assembly Group, made up of the barrel assembly, optic rail, handguard, gas system and charging handle;
The Receiver Assembly Group, primarily the serialized steel receiver, butt pad, recoil buffer and heat shield / cheek rest;
The Bolt Assembly Group, consisting of the bolt carrier, guide rod, recoil spring and bolt assembly and;
The Grip Assembly Group, containing the fire controls, trigger and hammer mechanism, magazine well and ejection port.

The RDB operates using the short-stroke piston system, firing from a closed bolt. A gas regulator is built into the Barrel Assembly Group to allow the operator to adjust the amount of gas used to cycle the action. The RDB uses a unique downward ejection method to permit the operator to fire the rifle from either side. During the extraction and ejection cycle, spent casings are dragged rearward over the magazine to the ejection chute located directly behind. The RDB bolt uses dual ejectors to assist in positive ejection, and has been demonstrated to operate normally even if the rifle is turned upside-down.^[6] While other bullpup rifles (FN 2000, Kel-Tec RFB, Desert Tech MDR) have used forward-ejection to allow ambidextrous use, these solutions tend to add parts and complexity to the design. Other bullpups can be converted to eject from one side to the other (IWI Tavor, Steyr AUG) but may not be able to do so without special parts.

Variants

RDB-17 - The standard RDB model for US market, chambered in 5.56 NATO with a 17.2” barrel with a 1/7 twist.^[3]
RDB-20 - Identical to the RDB-17, but with a 20" barrel.
RDB-C - Similar in operation to the RDB-17, the C model uses a 'hunter' style grip and a modified handguard.^[2]
RDB Survival - Similar to the RDB-C, the Survival model shares the 'hunter' grip paired with a lighter 16" barrel and comes with folding iron sights.^[7]^{[better source needed]}

All variants accept AR-15 STANAG magazines. They feature an ambidextrous bolt release and a manually locked back charging handle.^[4]

M43

The Kel-Tec M43 is a similar design replacing polymer parts with parkerized steel or with wood for the stock furniture. Compared to RDB models, it has additional integral folding sights and a heat shield over the short stroke piston.^[4]

References

^ Kellgren, George. "Hollow hammer with downward ejecting chamber". US Patent and Trademark Office. Retrieved 12 December 2021.
^ ^a ^b "Shot Show 2016 – Kel Tec RDB-C". Soldier of Fortune. Archived from the original on 2017-02-14. Retrieved 2017-02-13.
^ ^a ^b ^c ^d "The Kel Tec RDB". Kel-Tec. Retrieved 2017-02-13.
^ ^a ^b ^c "M43 BULLPUP". Blue Book of Gun Values. Archived from the original on 30 October 2017. Retrieved 28 October 2017.
^ "RDB-17 Manual" (PDF). Kel-Tec. Archived from the original (PDF) on 2017-02-14. Retrieved 2017-02-13.
^ "New Kel-Tec RDB Bullpup Rifle". Military Arms Channel. Retrieved 2015-10-15.
^ "New From Kel-Tec: KSG-25, RDB Survival – SHOT Show 2017". Truth about Guns. Retrieved 2017-02-13.