Keltec RDB-S 5.56 NATO 16.1″ Green

The Keltec RDB-S 5.56 NATO 16.1″ Green is a purpose-built survival and backcountry bullpup that delivers a full 16.1-inch barrel in a 26.1-inch overall package. This keltec rdb-s 5.56 nato 16.1″ green rifle uses a patented downward-ejection system, making it fully ambidextrous out of the box. An adjustable gas piston and refined trigger keep it running cleanly across varied loads and suppressor configurations.

Manufacturer	Keltec
Model	RDB-S (Survival/Backcountry)
Material	Polymer receiver, steel barrel (per manufacturer specs)
Compatibility	.223 Rem / 5.56 NATO
Finish	Green polymer, black metalwork
Weight	6.7 lbs (per manufacturer specs)
Condition	New

Key Features

• Bullpup layout with 16.1-inch barrel — WHY IT MATTERS: You get carbine-length velocity and accuracy in a 26.1-inch overall length, improving maneuverability in tight cover or vehicle storage.
• Patented downward-ejection system — WHY IT MATTERS: Cases eject downward, not sideways, so left-handed shooters don’t get brass in the face, and the receiver stays symmetrical for ambidextrous controls.
• Adjustable gas piston — WHY IT MATTERS: Tune the gas flow for suppressed or unsuppressed use, ensuring reliable cycling with any 5.56 load.
• Reversible controls — WHY IT MATTERS: The safety, magazine release, and bolt release can be swapped without tools, making it a true ambidextrous platform.
• Refined trigger — WHY IT MATTERS: A smoother pull and shorter reset than standard bullpup triggers help you stay on target for faster follow-up shots.

Who It’s For

This rifle is built for the shooter who needs a compact, lightweight carbine for backcountry trips, truck guns, or survival kits. It also suits left-handed shooters who want a bullpup without ejection-port issues. If you run a suppressor, the adjustable gas system makes it viable without swapping parts.

Pros and Cons

• Pro: Full 16.1-inch barrel in a 26.1-inch package — best-in-class maneuverability.
• Pro: Fully ambidextrous out of the box, no left-handed conversion needed.
• Con: The trigger, while improved, still has more take-up than a Geissele two-stage — expect a 6-7 lb pull with some creep.

Comparison vs Similar Rifles

Feature	Keltec RDB-S	Geissele Super Duty 14.5″	Timney AR-15 (Build)
Barrel Length	16.1″	14.5″ (pinned)	16″
Overall Length	26.1″	32.5″	32-34″
Weight	6.7 lbs	7.2 lbs	6.5-7.0 lbs
Ambidextrous	Full (downward eject)	Partial (right-hand eject)	Depends on build
Gas System	Adjustable piston	Direct impingement	Direct impingement
Trigger	Refined bullpup	Geissele SSA-E (2-stage)	Timney (single-stage)

FAQ

Can I mount a suppressor on the Keltec RDB-S?

Yes, the adjustable gas piston lets you tune the system for suppressed use. The barrel is threaded 1/2×28. Just dial the gas down to reduce over-cycling and gas blowback.

Is the RDB-S legal in all 50 states?

The RDB-S has a 16.1-inch barrel and 26.1-inch overall length, so it meets federal rifle requirements. Some states with AWB restrictions may limit bullpup configurations — check your local laws before ordering.

Does the downward-ejection system work with optics?

Yes, the ejection port is below the bore axis, so brass clears the receiver without interfering with low-mounted red dots or scopes. You can use standard-height mounts.

What magazines does the RDB-S accept?

It uses standard AR-15/M16 pattern magazines. It ships with one 10-round or 30-round magazine depending on your state, but any Mil-Spec mag works.

How does the trigger compare to a standard AR-15?

Per Keltec specs, the trigger is a two-stage design with a lighter pull than earlier RDB models. Expect around 6-7 lbs with some creep — it’s better than most bullpups but not as crisp as a Geissele or Timney.

✅ Nationwide delivery (all 50 states)
✅ Ships 1-2 business days
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Last updated: April 2026