The Kel-Tec RDB20 5.56 NATO 20in Tan Bullpup is a compact, fully ambidextrous semi-auto rifle that packs a full 20-inch barrel into a bullpup layout. Its downward ejection system keeps brass clear of your face and lets you shoot from either shoulder without swapping parts. It accepts standard AR-15 magazines and runs on an adjustable gas piston system, so you can dial it in for different loads or a suppressor. This is a practical, modern rifle for shooters who want a long barrel in a short package.
| Specification | Detail |
|---|---|
| Manufacturer | Kel-Tec |
| Model | RDB20 |
| Material | Polymer stock, steel barrel and action (per manufacturer specs) |
| Compatibility | Standard AR-15 magazines (5.56 NATO / .223 Rem) |
| Finish | Tan (flat dark earth) |
| Weight | Approximately 7.9 lbs (unloaded) |
| Condition | New |
Key Features
- Downward Ejection – Why it matters: Spent cases drop straight down out of the action, so lefties and righties can shoot without brass hitting them, and the rifle stays compact with no side ejection port.
- 20-Inch Barrel in a Bullpup – Why it matters: You get the velocity and accuracy of a full-length barrel in a rifle that’s only about 28 inches overall, making it easy to maneuver in tight spaces or store in a safe.
- Adjustable Gas Piston System – Why it matters: Tune the gas to match different ammo types or suppressors, reducing recoil and keeping the action running smoothly.
- Ambidextrous Controls – Why it matters: The safety, magazine release, and charging handle are all reversible or dual-sided, so any shooter can operate it naturally without aftermarket parts.
- Standard AR-15 Magazine Compatibility – Why it matters: Use the mags you already own for your AR, no proprietary nonsense. This cuts down on gear costs and makes reloading faster.
Who It’s For
This rifle is built for recreational shooters who want something different from a traditional AR, and for first-time buyers who want a compact, easy-to-handle gun that still delivers full-power 5.56 performance. It’s also a solid pick for left-handed shooters tired of brass in the face, or anyone looking to run a suppressor without a gas-heavy action.
Pros & Cons
- Pro: Compact overall length (28 inches) with a 20-inch barrel – great for home defense or truck guns.
- Pro: Downward ejection means no brass hits you, no matter your shooting stance.
- Pro: Adjustable gas system lets you fine-tune for suppressor use or weak ammo.
- Con: The trigger is heavier and has more creep than a good AR trigger – it’s serviceable but not match-grade. Aftermarket upgrades are available but require some work.
Comparison
| Feature | Kel-Tec RDB20 | Geissele Super Duty 16″ | Zev Technologies OZ9C |
|---|---|---|---|
| Action | Bullpup semi-auto | Traditional AR-15 | Pistol (not rifle) |
| Barrel Length | 20 inches | 16 inches | 4.5 inches |
| Overall Length | 28 inches | 33.5 inches | 7.5 inches |
| Weight (unloaded) | 7.9 lbs | 6.5 lbs | 1.7 lbs |
| Magazine Compatibility | AR-15 mags | AR-15 mags | Glock mags |
| Ejection | Downward | Right side | Right side |
| Price | $860.47 | $1,850+ | $1,200+ |
The RDB20 offers a unique bullpup design at a budget-friendly price compared to premium ARs like the Geissele Super Duty, but it’s not a direct competitor in trigger quality or precision. The Zev OZ9C is a pistol, so it’s a different category entirely – included here to show the RDB20’s rifle advantages.
FAQ
Does the RDB20 use standard AR-15 magazines?
Yes, it accepts all standard AR-15 magazines (5.56 NATO / .223 Rem). No proprietary mags needed.
Is the RDB20 truly ambidextrous?
Yes, the downward ejection design means lefties and righties can shoot it without brass hitting them. The safety, magazine release, and charging handle are also reversible or dual-sided.
Can I use a suppressor with the RDB20?
Yes, the adjustable gas piston system lets you reduce gas flow for suppressor use. The barrel is threaded 1/2×28 for standard muzzle devices.
How long is the overall length?
The RDB20 is about 28 inches long overall, thanks to its bullpup layout. That’s shorter than a standard 16-inch AR-15.
What’s the barrel twist rate?
It’s 1:7 twist, which stabilizes heavier bullets (55-77 grain) well for accuracy.
Ready to Buy?
Get the Kel-Tec RDB20 5.56 NATO 20in Tan Bullpup for $860.47 – a compact, ambidextrous rifle that delivers full-size barrel performance. According to industry data, bullpup rifles represent about 5% of the U.S. semi-auto market, but their popularity is growing among shooters who want a short overall length without sacrificing barrel length. This is a solid entry point into that world.
- ✓ Nationwide delivery (all 50 states)
- ✓ Ships 1-2 business days
- ✓ 30-day returns
- ✓ Secure checkout
Check out more options in our Semi Auto Rifles category, or see other Bullpup Rifles and 5.56 Rifles.
Last updated: April 2026
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