[Review] Kel-Tec RDB-S: Little Bullpup That Could

There are some in the American gun community who subscribe to the idea that the bullpup is an inferior design.  

I am not a card-carrying member of this group and I can firmly tell you this after trying the Kel-Tec RDB-S.

KelTec RDB
She’s a sexy beast, I believe John-117 would absolutely approve!

I was recently allowed to take the new rifle out for a test drive and my impressions are favorable.  

Evolving the survival rifle is an ambitious undertaking but if anyone is up to the task it is Kel-Tec, a company with a storied history of pushing firearms boundaries.

Best Starter Bullpup
at E-Arms

Prices accurate at time of writing

Prices accurate at time of writing

Let me bend your ear for a moment, dear reader, and tell you why.

There have been a number of survival rifles over the years and one of the chief models of this design is the AR-7 created by Eugene Stoner himself.  

Stoner was more famously known for creating the AR-10, and subsequently, the ubiquitous AR-15 which you can find nearly everywhere these days.

Survival Rifle Beginnings

What’s the idea behind a survival rifle?  

Well, it started with wartime pilots, flying and fighting over hostile territory.  The cockpit is a small area indeed so traditional armament was a bit too big to tuck away under a seat.

The AR-7 was small and broke down to store in its own stock for an even smaller overall footprint. Should a pilot crash, they wouldn’t be charging the enemy position on their own with the .22 long rifle caliber wonder gun, but they could carefully sustain themselves on a diet of small game harvested with the rifle.  

Let’s evolve that threat a little and consider that the cockpit isn’t the only place you might encounter a survival scenario anymore.  Kel-Tec has designed a gun in the RDB-S that does not need to be assembled, it is all one piece.

You simply pull it out and go to work.  In addition, the rifle shoots the admirable .223 caliber round and feeds from AR-15 magazines. Sure, some will argue ballistics but most would admit, upgrading from a .22 long rifle to a .223 is a big deal.  Now maybe storming the enemy position is not so out of reach.

(L to R) 22LR, 9mm, Five-Seven, 5_56
(left to right) .22LR, 9mm, 5.7x28mm, .223/5.56

Compact with a Twist

At just over 26 inches, the rifle is smaller than anything you could assemble short of a tax stamp (SBR or pistol).  

With a Vortex SPARC AR mounted to the rail above the forend, the test model weighed in at 6 pounds, 6.6 ounces, unloaded.  This is par with average weights for an AR-15 carbine with a 16-inch barrel, which the RDB-S also has.

KelTec RDB
Left-handed shooters will love the penalty free ejection port.

The bullpup design takes advantage of moving some things around to shorten the overall profile of the rifle.  This is its chief advantage. There is of course, a barrel, a chamber, magazine well, trigger, buttstock and grip, but they are moved toward the rear of the rifle.  

The RDB-S actually has an ejection port in the bottom of the rifle’s buttstock.  This means that shell casing shoot out toward the ground. This might make you a more popular shooter to your right since you won’t be firing hot brass in the direction of your shooting partner.  

Left-handed shooters rejoice!

Here is a rifle that will not shoot brass onto your arm. The actual chamber is just below where you establish cheek weld.

From the cheek to the muzzle is all barrel shrouded with the handguard.  The trigger guard and trigger are forward, and your optic is well forward of the receiver. This is a pretty new concept unless you’ve shot a scout squad configured rifle.

Controls are comfortably ambidextrous though the charging handle is on the left side.  I love this thing because it brought back some distant memories of running an MP-5. The charging handle pulls back and then locks in place by canting it slightly up and releasing.  

Once you load or reload a magazine, slapping that charging handle down is all you need to do before you’re back in the fight. For some reason, it’s more satisfying than pulling a T-handle charging handle of an AR.  Once in the forward position, the handle neatly folds forward out of the way.

Overall the gun is a meld of waffle-shaped (green) polymer exterior covering steel parts on the interior. The stock is adjustable for length of pull, giving you roughly, an additional two inches to tuck into your shoulder pocket.  

The grip is not a vertical, downward shaft, but more akin to a traditional shotgun grip, with a downward curving swell running back from the trigger guard.  It was comfortable and I had no complaints holding it either up to my shoulder or in a low ready.

The Picatinny Rail above the barrel runs the length of the action from the rear of the charging handle to just a couple of inches before the muzzle.  Here I mounted a Vortex SPARC AR red dot.

at Amazon

Prices accurate at time of writing

Prices accurate at time of writing

Although it had no magnification, I was really impressed with the results of pairing this optic with the rifle.  

[Ed: the SPARC did great in our Best Red Dots Under $200 testing]

Best Budget Red Dots
Best Budget Red Dots

At either end of the rail, there are iron sights mounted and they are also adjustable. Simply flipping them up or down puts them into play or stows them away.  

I love running an optic but considering this rifle is marketed for survival, it’s smart to have redundant backup.

Testing…Attention, Please!

Over the course of a few different trips to the range, I tried out different aspects of the RDB-S.  

This thing is really easy to drive through CQB environments like a house. Also, if you’re the type to switch shoulders on support side corners, the gun really feels at home there.  

It feels light and inimitably maneuverable.

One might think this would sell you short on accuracy, and if it were an AR-15 it would likely be true. However, despite its short length, you have to remember there is still a 16-inch barrel in there.

KelTec RDB
Having lost bikini-type covers for optics before, I love this captured lens cover feature on the SPARC AR.

With the Vortex SPARC AR mounted up I zeroed it in at 50 yards.  This seemed like a happy medium. From a rest at the bench, I was able to obtain a five-shot group at just less than an inch using Winchester 55-grain FMJ.  

Encouraged, I eventually stretched out to 100 yards using Hornady Black 62-grain. That is a pretty big ask for my eyes without magnification, but I dialed down the intensity of the dot, controlled my breathing, and still came up with groups averaging in the 3-inch realm.  

at Lucky Gunner

Prices accurate at time of writing

Prices accurate at time of writing

I was really tickled with these prospects. Being able to sight in up close is, of course, critical, but being able to reach out gives the RDB-S far more versatility for a gun you can pull out of a backpack.

KelTec RDB target
A 50-yard group with the unmagnified SPARC AR.  This rifle is diverse enough that with bigger glass it could do even more.

I should note I was using Magpul mags of the 10-round variety.  This made setting up my shooting rest easier and unobstructed. When it was time to get down, the 30-round mags were handy. Everything ran like a greyhound.

The only malfunction I experienced was me not seating the magazine properly, causing a failure to feed.  

This is a different weapon system so these types of things are to be expected—especially when muscle memory is screaming for me to jam that mag forward of the trigger, not behind!  

Yes Buy It, But Be Ready to Train

Someday someone will probably design the perfect rifle, capable of doing all the things we’d love for it to do.  When that day happens, the design will likely come from Kel-Tec, or a company like them who is willing to push things a bit.  

The RDB-S is a superb rifle with a lot of potential.

You could easily be happy by mounting up a red dot, or you could add a scope for distance and maybe some offset irons for up close and personal.  Either way, you’d have a great setup. I found the gun to be accurate and reliable, testing through a few hundred rounds of both Hornady and Winchester in different weights.

I did not see any inherent flaws with the bullpup design (other than my unfamiliarity).  In fact, there are a lot of advantages. The recoil was different than I was used to, perhaps a bit more than an AR-15.  

This is likely because the weight is distributed differently than an AR, but it was definitely manageable.

In fact, the only thing I didn’t like about the RDB-S was that it wasn’t beard friendly for me but this is a small matter, easily adjusted to.  Maybe I should invent a bib to protect shooters with beards!

KelTec RDB
Stare long enough and you’ll see my Viking heritage in this impromptu DNA sample!

The trigger held some surprise for me.  

There was a bit of travel in the front, perhaps a millimeter or more, then a definitive wall.  Pulling back just slightly more would send my shot downrange. It feels like a two-stage and although I did not confirm this, I took advantage of it when making my longer shots.  

Testing with the Lyman Digital Gauge from Brownells was a bit of a challenge because of the structure of the rifle, but what I got back averaged was just under two pounds (note: this could be off due to the angle of pull afforded).

The bottom line is, anytime you use a new weapon system, you need to train with it.  

Now I’m not saying you need to build a SWAT obstacle course/live fire range in your backyard and put in some quality time with the rifle—I lied, I am saying that—but if you might deploy the rifle under any kind of stress, you need to know it well enough that its basic functions are close to autonomic for you.


  • Caliber: .223
  • Weight (unloaded): 5 lbs 14 oz
  • Magazine Capacity: any AR-15 compatible magazine
  • Overall Length: 26.1″
  • Barrel Length: 16.1″
  • Twist Rate: 1:7
  • Trigger Pull: 4 lbs

By the Numbers

Reliability 5/5

I found this rifle entirely reliable in function.  The only questionable portions were strictly my own, based on unfamiliarity with the platform.  As I mentioned earlier, I failed to properly seat a magazine in one instance causing a failure to feed.

Customization 2/5

I’m not seeing too much that is customizable on the RDB-S at this point but I suspect the rifle will become popular enough to support one.  There is at least a trigger spring available from the fine folks at M*CARBO—look to them for even more upgrades in the future.

The Picatinny rail on top seems to be the only place offering options on the rifle at this point, so side mounting a light or any other accessories appears to be limited at this time.  I understand the furniture from other RDB models are interchangeable with the “S”. Of note, however, I believe the design aesthetic, or the rifle’s intended purpose, is a sleek, thin weapon that can be toted and deployed snag-free.

That said, there is a location on the front and rear of the rifle to mount a sling (check out our Best Rifle Slings).  So while the overall package is somewhat austere, it has the necessities.

Looks 4/5

Bullpups are intriguing to the eye and this one does not disappoint.  It reminds me of a few guns I’ve deployed to battle the Covenant in the many Halo games over the years.

Price 4/5

Kel-Tec’s website lists the RDB-S with an MSRP of $1,456 and I found online prices averaging in the $1,000 range.  I feel like this is a fair (perhaps even good) price for what you’re getting—a compact, two-foot-long, semi-auto rifle that fires a .223 round accurately.

Overall 4/5

This is a cool little rifle that can serve a lot of roles!  You could store it somewhere as a “just in case” contingency rifle; imagine your truck or a cabin somewhere.  It would serve admirably as a home defender, navigating corners ninja-like and not bouncing hot brass off walls back into your face.  The .223 is large enough to harvest survival game so there are uses within this realm also. Kel-Tec has come up with a package targeted toward survival, but this rifle can do that and a whole lot more.

Parting Shots

Survival rifle, home defense, tactical door-kicker, awesome plinker – the Kel-Tec RDB-S can fill a lot of roles if you want it to.

We’ve seen some cool stuff from Kel-Tec over the years, like the Sub-2000 folding pistol carbine, and hopefully, we will continue to enjoy new and interesting innovations from them.

Best Starter Bullpup
at E-Arms

Prices accurate at time of writing

Prices accurate at time of writing

What do you think about bullpups? Use one for home defense or SHTF? Let us know in the comments! Need more bullpup awesomeness? Take a look at our Top 9 Bullpup Rifles & Shotguns

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