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Kel-Tec RDB (series)

Semi-Automatic Bullpup Rifle [ 2015 ]

A bullpup configuration, accessories support, and use of the 5.56mm cartridge are just some of the qualities of the impressive Kel-Tec RDB series.

Authored By: Staff Writer | Last Edited: 02/02/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

Founded in 1991 by Swede George Lars Kellgren, Kel-Tec CNC Industries, Incorporated has gone on to successfully broaden its market appeal as well as its range of product offerings. Designed by Kellgren himself, the "RDB" ("Rifle, Downward-ejection, Bullpup") continues the long and storied line for the company and was introduced in 2015. Today, the series includes the RDB-17, RDB-20, RDB-C, RDB-Defender, RDB-Hunter, and RDB Survival as primary variants.

The RDB designation itself details the weapon as it is a traditional rifle sporting a downward-ejecting spent cartridge system and is arranged in "bullpup" configuration. The bullpup arrangement has several advantages when compared to a traditional-arranged rifle system: the action and feed are both contained in a fixed housing aft of the grip and trigger section allowing for a full-length barrel to be used while still keeping overall length of the gun shorter than normal (the barrel is embedded in the remaining space of the housing and run through the forend). However, this makes for an oversized shoulder stock, brings the action / ejection process closer to the firer's face, and presents muzzle dangers if the weapon is not respected. Nevertheless, the arrangement has been proven through a myriad of firearms designs spanning decades and is a widely-accepted tactical solution for many militaries of the world today.

In the series, the "RDB-17" represents the base model form with its downward-ejection system, bullpup configuration, and "17 points" (17.3 inches) to the barrel length. A Zytel forend and integrated Picatinny rail system are standard as is the ambidextrous nature of the design (supporting both left- and right-handed shooters, the downward ejection system making this possible). The accessories rail arrangement allows for mounting of various tactical options over-and-under the weapon. The barrel's muzzle is slotted and the grip handle showcases an elevated pattern for a firmer hold.

The design is chambered for the readily-available 5.56x45mm NATO / .223Rem intermediate rifle cartridge. Weight reaches a manageable 7lb and the standard magazine count is 20-rounds (marketing suggests support for AR-15 STANAG magazines as well). As expected, the magazine is inserted into a well aft of the trigger unit and pistol grip. Overall length of this version reaches 27.3 inches and the trigger pull rating is reported at 4.5lb to 5.5lb. The internal action relies on a short-stroke (closed bolt), gas-operated, rotating bolt system of operation.

The entire system is designed to be modular, breaking down into four major sections containing their respective components (receiver assembly, grip assembly, bolt assembly, and barrel assembly).

The RDB "Survival" is a more compact, lightened form of the base RDB-17 and intended for back country work. A 16-inch long barrel assembly is used to keep dimensions compact and reduce weight in the process. Folding sights and a collapsible stock are both standard and sight devices are positioned at the aft-end of the Picatinny rail over the weapon and at the muzzle to enhance accuracy-at-range.

The RDB "Defender" takes the proven qualities of the original RDB-17 and the RDB Survival to produce a lighter weight 5.56mm tactically-minded solution. The handguard is of an M-LOK design and constructed of durable, lightweight aluminum. The stock is collapsible to shorten the overall length of the weapon some more. As in the Survival, the barrel of the Defender measures a handy 16-inches long, keeping dimensions in check, while the forend is shrouded in a perforated cooling jacket, the muzzle slotted, and the grip handle ribbed. A section of rail is set over the gun for the fitting of accessories, typically sighting devices or aimers.

The RDB "Hunter" takes the tactical features of the RDB-17 to the hunting market to produce a useful, portable bullpup solution. The stock housing the action and feed is fixed/solid and the forend elegantly styled with a tapering effect applied from rear to front. A swiveling bipod assembly can be fitted to the forend for stability when set-aiming, a section of Picatinny rail is installed over the forward half of the frame, and a 20-inch threaded barrel rounds out the features of this unique firearm.

The M43 is a related development featuring "parkerized" (a phosphate conversion coating process used to combat corrosion at key parts) steel or wood at the stock, replacing the original polymer housing. Folding sights and a heat shield are standard qualities of this offering.©MilitaryFactory.com
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Service Year

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Semi-Automatic Bullpup Rifle

Kel-Tec CNC Industries, Incorporated - USA
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Compact nature allows for relatively easy concealment.
Design sets the action behind the feed, allowing for a more compact design retaining a full-length, or near-full-length, barrel assembly.
Internal action allows release of single round per trigger pull, actuating a semi-automatic loading mechanism for successive shots.
An automatic, or pseudo-automatic, function is built into the system, allowing for repeat firing to be achieved.
Supports mounting of optics (scopes) to aid in accuracy for ranged fire.
Design allows for user adjustability of certain components for customization.
Design offers mounting points for external, after-market hardware including laser aimers, flashlights, scopes, and grips.

Overall Length
693 mm
27.28 in
Barrel Length
439 mm
17.28 in
Empty Wgt
6.61 lb
3.00 kg



Short Stroke; Gas-Operated; Rotating Bolt; Semi-Automatic

One shot per trigger pull; self-loading or auto-loading action aided by internal mechanism; trigger management (and initial cocking) typically required by the operator; subsequent shots are aided by the unlocked / moved bolt.
Rotating Bolt
System utilizes internal mechanism to lock the breech or rear barrel assembly prior to firing.
Gas-operated system is featured, typically involving a gas cylinder and rear-driven piston directing energy to the bolt component.
(Material presented above is for historical and entertainment value and should not be construed as usable for hardware restoration, maintenance, or general operation - always consult official manufacturer sources for such information)


5.56x45mm NATO / .223Rem

Sample Visuals**

Graphical image of a 5.56mm intermediate rifle cartridge
Rounds / Feed

20-round detachable box magazine.
Cartridge relative size chart
*May not represent an exhuastive list; calibers are model-specific dependent, always consult official manufacturer sources.
**Graphics not to actual size; not all cartridges may be represented visually; graphics intended for general reference only.
RDB - Base Series Name.
RDB-17 - Base model; 17.3 inch barrel length; Zytel forend assembly; Picatinny over-under.
RDB Defender - Tactical model; M-LOK aluminum handguard; 16 inch barrel length.
RDB Hunter - Hunting rifle version; traditional stock housing; tapered forend; over-frame rail section; 20 inch threaded barrel.
RDB Survival - Back Country shooting model; compact / lightweight; 16 inch barrel length; over-frame rail section; muzzle-mounted forward sighting device with over-frame rear device.

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Image from Kel-Tec marketing materials.


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