Description

Kel-Tec RDB Carbine — The Downward-Ejecting 5.56 Bullpup

The Kel-Tec RDB solves the problem that kept bullpup rifles off most American shooters’ shortlists: ejection. Where conventional bullpups throw brass sideways into a left-handed shooter’s face, the RDB drops spent cases straight down through a vertical chute behind the magazine well. The result is a genuinely ambidextrous 5.56 carbine that packs a 17.3-inch barrel into a 27.3-inch overall length.

How the Downward Ejection System Works

RDB stands for Rifle, Downward-ejecting Bullpup. A rotary bolt with a spring-loaded ejector and a downward-facing extractor pulls the spent case rearward along the top of the magazine, then releases it into a chute that vents beneath the receiver. The hammer is U-shaped and rides outside that chute. Bolt travel is longer than a conventional carbine’s, which the Kel-Tec RDB turns into an advantage: ejection is gravity-assisted and the bolt carries more energy into the feeding cycle.

For the shooter, the practical payoff is simple. Brass and gas leave your line of sight entirely. You can shoot from either shoulder, run the rifle around either side of a barricade, and hand it to a left-handed shooter without touching a thing.

Key Specifications

Kel-Tec RDB Carbine at a glance:

• Caliber: 5.56x45mm NATO / .223 Remington
• Barrel length: 17.3 inches (439mm)
• Overall length: 27.3 inches (693mm)
• Weight unloaded: 6.7 lbs (3.0 kg)
• Twist rate: 1:7
• Trigger pull: 4.5–5.5 lbs
• Magazine: Accepts standard AR-15 pattern magazines
• Action: Semi-automatic, gas operated, adjustable gas system

Why the Bullpup Layout Matters Here

A 17.3-inch barrel in a 27.3-inch package is the whole argument. A conventional AR-15 with the same barrel runs about 36 inches with the stock collapsed — roughly nine inches longer. You keep full-length barrel velocity and a legal rifle configuration without the maneuverability penalty, which is why the Kel-Tec RDB appeals to shooters working in vehicles, blinds, and tight indoor spaces.

The 1:7 twist stabilizes heavy bullets well, so the rifle handles 62- to 77-grain loads without complaint alongside standard 55-grain range ammunition. Stock up on .223 and 5.56 ammunition before your first range trip, and browse the full rifle ammunition selection for match and hunting loads.

Ammunition, Gas Setting, and Magazines

The chamber is cut for 5.56 NATO, which means it safely handles both 5.56 and .223 Remington. The reverse is not true — a rifle chambered in .223 should not be fed 5.56, a pressure distinction documented by SAAMI. Because this rifle is 5.56-chambered, you have the full range of both.

The adjustable gas system is what makes the Kel-Tec RDB flexible. Tune it down for lighter loads or when running a suppressor, open it up for steel-case bulk ammunition. Magazines are standard AR-15 pattern, so most of what is already in your range bag will drop straight in.

Suppressor and Optics Notes

The RDB is a popular suppressor host precisely because the gas system is adjustable and the ejection path keeps gas away from your face. Note that suppressors are regulated under the National Firearms Act and require a separate federal transfer process through the ATF; they are not included and are not available through this listing.

This listing is for the rifle only. Optics, lights, slings, and magazines shown in photography are not included. The top rail accepts standard optics; a low-mount red dot suits the bullpup cheek weld better than a tall AR-height mount.

Who This Rifle Suits

Left-handed shooters get the most obvious benefit — this is one of very few 5.56 rifles that is truly neutral to which shoulder you use. Beyond that, the Kel-Tec RDB draws truck-gun and home-defense buyers who want rifle ballistics in a short package, competitors in bullpup-friendly divisions, and shooters who simply want something other than another AR-15 at a working-rifle price point.

FFL Transfer and State Restrictions

This is a modern semi-automatic centerfire rifle. Federal law requires that it ship to a licensed FFL dealer in your state for transfer and background check — it cannot be shipped to a residential address. Provide your dealer’s FFL information after checkout.

Several states and municipalities restrict or prohibit semi-automatic rifles with detachable magazines, and magazine capacity limits apply in others. Bullpup configurations face additional restrictions in some jurisdictions. Verify that the Kel-Tec RDB is legal at your delivery address before ordering; see our terms and conditions for full shipping and compliance policy, or contact us with questions about your state. Buyers must be 18 or older for long gun purchases under federal law, with some states requiring 21. Guidance on safe storage and transport is available from the NSSF.

Browse more rifles available online or return to the full catalog.