Keltec RDB-S 5.56 NATO 16.1″ Green
About this product
Compact 5.56 bullpup with 16.1-inch barrel in a 26.1-inch package, fully ambidextrous downward-ejection, and adjustable gas piston for survival or backcountry use. Green finish.
Available for delivery across the United States.
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