Review: Kel-Tec RDB

Ladies and gentleman, the future is here. The smartphone has revolutionized antisocial behaviors, reality television has dumbed down society and worked its way into our government, and consumer rifles are once again feeding from their butts… Yes, I’m talking bullpups; the strange corner of firearm technology that places the trigger and pistol grip in front of the action. It’s the pattern of firearm that 50s and 60s futurists claimed would be the weapon of the future… But were they right?

Bullpups have been around since, at least, the early 1900s. Firearms like the British Thorneycroft carbine and French Faucon-Meunier came about in the first 20 years of the 20th century, but it wasn’t truly until the latter half of the 20th century when the bullpup began to gain traction. The development of the British EM-1 and EM-2 rifles led to production of the SA80 series of rifles, and ultimately the L85 currently in use by the British Military. The Russians had the SVU pattern of Dragonov and ОЦ-14 (OTs-14) Groza. The French have the FAMAS, and the Austrians have the Steyr AUG. Bullpups definitely have made their mark around the world. But what do the Americans have? The Bushmaster M17S? BARF. No wonder interest died away in the 90s.

However, in the past 20 years or so, we’ve seen a resurgent interest in modernized bullpup weapons. Firearms like the Singaporean SAR-21, the IWI Tavor, FN2000, and the chub-inducing Desert Tech MDR were all born of the past two decades, and the interest in bullpups is only increasing. Futuristic designs, modern CNC machining techniques, and forward thinking ergonomics brought has brought the bullpup back into the spotlight. But, with all of that ‘forward thinking‘ came a hefty price tag. But, rising out of the Florida swamps comes Kel-Tec with something different…

Gun Specifics
Firearm: Kel-Tec RDB
Layout: Bullpup, downward ejection
Caliber: 5.56 NATO – 1 in 7″ Twist Rifling
Barrel Length: 17.3″
Operating System: Manually Regulated Short Stroke Piston
Sight Mounting Options: Picatinny Top Rail
Furniture: Black Polymer
Magazine: Standard AR-15 Magazine


Following the RFB and KSG, the Kel-Tec RDB (or ‘Rifle, Downward-ejection, Bullpup) is the third bullpup long gun develped by Kel-Tec. Chambered in 5.56 NATO, it utilizes a short stroke gas piston, is fed from AR-15 pattern magazines, and sports some fairly innovative design elements. While the RDB certainly isn’t the most beautiful gun in the world, it does have a rather industrial and functionalist look to it. Aside from aesthetics, one of the first things you might notice is that the gun is unfairly priced compared to every other modern bullpup on the market. Priced at under $1000, the RDB’s nearest competitor is the IWI Tavor, sitting at an MSRP of $1999, making the RDB the most affordable bullpup in the neighborhood.

Design wise, the rifle is almost fully ambidextrous. The safety is located on both sides of the gun, the magazine release is located centrally in front of the magazine well and is easily activated with either hand, the bolt stop/release is on both sides of the gun, and most importantly, the spent cases are ejected downward rather than to the side. The only reason I say it’s ‘almost‘ ambidextrous is that the charging handle is only located on one side of the rifle. You can swap the charging handle to the other side, but you must disassemble the rifle to do so… So, it’s mostly ambidextrous.

As for looks, the gun carries the peculiar lines of any bullpup, but sports those distinctive Kel-Tec alligator-like bumps molded along the gripping surfaces of the gun. Being from Florida, I suppose that makes sense. While the gun might be priced affordably, the gun in no way feels cheap. In the hands, the RDB is quite solid and comfortable. The length of pull is neither too short or too long, the grip angle is comfortable, and all controls are easily accessible. Although quite a bit of the gun is made from polymer, there is plenty of steel reinforcement where it counts to make the firearm a formidable brick shithouse. Be aware that the recoil pad is in no way secured to the buttstock, so it will fall off a few times before you decide to superglue it to the gun.


When you charge the weapon, the action is harsh, gritty, and noisy. Think of moving a heavy wooden box across pavement with gravel strewn about; it’s like that, but louder and more gravelly. Or, at least it will be until you lube the crap out of the recoil spring assembly… more on that later. While there is a bolt hold open/release feature on the RDB, the charging handle can rotate upward and lock back just like an H&K, so you can get your tacticool H&K slap on.

At this point, looking at the outside of the gun will do little to demonstrate the remarkably clever design that lies within the RDB’s exoskeleton. I suppose, like all things, it’s what’s on the inside that counts.

Field stripping the gun is in no way difficult. You push pins out, sections separate, and innards come out. The sections of the gun fit rather tight together, so once you push the take-down pins out, you will need to wiggle with extreme prejudice to separate the lower, front, and rear sections. Once everything is apart, you can see the unusual and peculiar design that makes this firearm so interesting.

One of the first things I noticed after I stripped this gun apart was the rather gigantic bolt carrier and recoil spring assembly that spans almost the entire length of the rifle. The bolt carrier is welded to a long operating rod that houses the recoil spring. In place of guide rails inside of the rifle, there is a long guide rod that is permanently within the captive recoil assembly, which lines everything up inside of the rifle. If you press the rear of the guide rod, you’ll compress the recoil spring inside of the operating rod and hear exactly where that gravelly and gritty sound is coming from. Apply a generous amount of your personal choice of lubricant to help remove the gravelly chafe.

The bolt is a seven-lug, asymmetric bolt with a large extractor and dual ejectors. It’s actually a fairly interesting design. It indexes into a pre-headspaced barrel extension, and cams against the bolt carrier to lock the action quite similar to an AR-15.

If you’ve ever handled a bullpup before, you’ll know that they are not necessarily known for having fantastic triggers. In addition, if you’ve ever handled Kel-Tecs before, you’d know that they too are not necessarily known for having good triggers (the P-11 being a prime example). But, hold your gators, because the clever mechanism behind the RDB’s trigger makes it remarkably palatable. If you were to compare it to a mil-spec AR-15 trigger, you might actually prefer the RDB trigger. It really makes you think about and question all of the prejudices you’ve developed throughout your life… Anyway, once you get over your introspective dilemma, you might wonder how they developed such a decent trigger. Among the many unique design elements, I find the trigger mechanism is by far the most interesting.

Most firearm trigger mechanisms are designed so all parts are close and inclusive to reduce flexing and slop during trigger pull. Most bullpup rifles keep their hammer and sear mechanisms close together like non-bullpup firearms, but that means they have a long transfer bar of some kind to span the distance from the far-away trigger to the rest of the fire control group. This increased size creates added friction and flexing from the trigger bar, and thus makes for a spongy, creepy, and generally shitty trigger.

Be that as it may, Kel-Tec has reversed the standard bullpup methodology and has made an extra-long sear engagement with a long transfer bar reaching back to the hammer. It’s a little hard to photograph with my crappy camera, but you can see from the photos the long sear extension engaging the trigger. This allows the trigger and sear mechanism to be in close proximity to each other, creating a more conventional feeling trigger break. It’s actually pretty damn clever.

Speaking of which, the RDB’s hammer certainly is a funky thing to look at. It’s oddly shaped, it has a strange travel path, and it’s obscenely loud when dry firing. How loud? It has to be almost 120db… It makes my ears ring just by dry firing. But aside from being loud and percussive, it actually does more than just slam into the firing pin. With its long travel, it acts as a secondary recoil spring, and ultimately, as a recoil buffer at the end of the bolt stroke. I am one to admit when I see something genuinely innovative, and this is innovative AF. Good job, Kel-Tec.

The most peculiar aspect of the RDB has to be its bottom ejection system. To accomplish downward ejection, the case is pulled over the top of and past the magazine, into the ejection port, then finally ejected by the dual spring-loaded ejectors.

The magazine release is kind of peculiar, also. It’s a single contact point that is accessible from the center of the gun, just behind the pistol grip. It’s essentially a U-shaped flat spring that pinches around the magazine well. By pushing back on the magazine release, the arms of the release slide out of the indexing slots; that allows the magazine to drop free. Quite honestly, I’m having a hard time describing the function… Just look at the photos.

The piston system is also rather unique. When you take the gun apart, the piston is held into the gas block by only the friction of the gas rings on the piston head. If you pull on the piston (the piston itself, not the return spring or return spring cup), it comes right out.

So how does it get held in place and not fly out during cycle? Well, the reason is rather clever. The spring on the back is actually the piston return spring. When the gun is assembled, the guide rod poking out of the front of the operating rod goes right into the little cup on the back of the piston return spring. When the gun fires, the outside edges of the piston act as a tappet, while the guide rod and piston return spring prevent the piston from exiting the piston chamber. So, not only does the guide rod keep everything lined up in the gun, it also retains the piston… clever girl…

Now that we are looking at this particular area of the gun, I suppose I can show you how the charging handle swaps.

The charging handle rests around the piston chamber when fully forward. To remove, you just pull back slightly on the charging handle, once clear of the piston chamber, pivot the latch outward, and finally pull forward. Reverse the procedure on the opposite side of the gun to install the charging handle. That’s it.

Shooting the RDB is rather interesting. Regardless of the large SpecWar brake on the front of this specimen, the gun recoils very gently. It’s kind of unusual, actually. I’ve shot a lot of different firearms, but the recoil impulse of this gun is very different. You definitely get the initial recoil pop of the round going off, but no *thud* of the bot carrier hitting the back of the receiver. It’s a very smooth and easy recoil; one that must be experienced to fully appreciate.

I suppose the last bit of this firearm’s anatomy that I haven’t covered is the gas regulation system. Herein lays the quirky aspect of the RDB you’ve probably been waiting for.

Since the RDB has an ejection system that involves going over the magazine, the prospect of a short stroke brings with it some very uncomfortable thoughts. If you don’t have the gas regulator set to allow enough gas into the piston, you are going to get a short stroke and a double feed… Let me tell you. A double feed in the RDB sucks. It sucks hard. Since the ejection port is behind the magazine well, the only way to access the breach is through the magazine well. This means that you have to stick your fingers into the gun’s cloaca… I mean magazine well… and hope you can poke your way to the promised land. There is not enough room to reach in and claw the obstruction out, so the best you can do is poke-a-poke-a-poke-a until the problem falls out. I’m not exaggerating either… that’s what you have to do.

Let’s do a little scenario, shall we? You are at the range, you fire your first shot, you release the trigger to reset, then come upon a dead trigger instead of a second shot. What is your first instinct? Is it pull on the charging handle? Well, that was my first instinct. Well, by doing so, you effectively start adding to the ‘Nth’ feeds.

You have a double feed to begin with, thus:
1st pull: triple feed
2nd pull: quadruple feed
3rd pull: quintuple feed

This will continue until the gun seizes up completely, or you fill the receiver full of jammed cartridges… Ok, that won’t actually happen. Once the double feed occurs, cycling the action just jams the double feeding cartridges into the chamber harder, making it harder to poke-a-poke-a the problem out.

Fortunately, you’ll probably know on the first pull something is wrong when you feel the charging handle empty until halfway through the pull. That’s a clear indicator that you’ve got a multifeed of some kind.  You can then lock the charging handle to the rear, remove the magazine, and begin your poke-a-poke-a to remedy the situation.

Long story short, get acquainted with the gas regulation system prior to doing any serious shooting with the gun… as in, know which direction to turn the regulator so you don’t sit there and crank the gas lower and lower instead of opening her up. I personally am not a fan of manually regulated gas systems. Why? Because I just want my guns to work. I don’t want to have to think, “If I put this ammo in, I’ve got to turn the regulator this many clicks this direction and blah blah blah.” I just want to be able to put ammunition in and run the gun… I digress…

Accuracy wise, the gun shoots pretty ‘meh’. I was able to get, at best, 2.5″ groups out at 100 Yards using Federal XM855 ammunition with a fixed magnified optic. It’s not great ammo, but I use it because it’s a fairly standard and available ammunition choice, and represents what many people will put through the gun. In this firearm, it demonstrated fairly mediocre accuracy.

Range Time Information:

Firearm: Kel-Tec RDB
Magazines: 30 Round Magpul PMag (x2)
Caliber: 5.56×45
Ammunition: Tula .223 Rem 55gr FMJ (60 rounds)
Federal XM855 5.56 NATO (62gr Green Tip)
Temperature: 68° Fahrenheit
Elevation: Somewhere between 50 and 100 Feet above sea level
Total Rounds Spent: 120
Final Disposition: Indifferent


  • Affordable
  • Very good bullpup trigger
  • Very soft shooting
  • Mostly Ambidextrous
  • Fairly Ergonomic
  • Innovative design


  • Not very common
  • Kind of ugly (HAH!)
  • Prone to double feeds (if not properly gassed — operator error, honestly)
  • Kind of heavy

So, is the future really here? Well, I suppose so. We’ve got refrigerators that can tell us when our milk is going bad, and then automatically post about it on social media, so I guess we can have affordable rifles that feed from their butts. Pointless yammer aside, the Kel-Tec RFB is actually a very solid and functional firearm. The engineering and design put into it is quite unique and very innovative, but the final product isn’t making my inner Owen Wilson say, “Wow!” While handling the gun, there is nothing exciting or remarkable about it. Don’t get me wrong, the gun is honestly very reliable and is fun to shoot, but it just does nothing for me. Some of you out there might really like the gun. I mean, some of you might ask, “DEAR GOD, WHERE HAVE YOU BEEN ALL MY LIFE?!” But, the greater likelihood will be that you won’t be trading in your trusty AK or AR for it.

In conclusion, If you are looking for an inexpensive bullpup that is functional, flexible, and ISN’T a garbage Bushmaster M17S, the Kel-Tec RDB is right for you… If I had the money, though, I’d rather get my hands on a Desert Tech MDR… But I don’t have the money… So I think I’ll just wait.


6 thoughts on “Review: Kel-Tec RDB

  1. Have been handling AR play form for most of my life- military, LEO, now civilian…..most often I carried an SBR- some suppressed, most not……I’m left handed but shoot equally both hands…….for the RDB
    I have put lots and lots of rounds through the RDB to make my conversion from the AR platform to the RDB——for me…I’m very much impressed with this weapon…the accuracy, the recoil, transition from left to right, reloading – all exceptional from a tactical shooting stand point….the HUGE advantage is the overall length of the weapon with a barrel length of such you loose no ballistics……..
    This has become the wespon of choice for me!
    Only thing I can’t say at the moment…while I have put it through plenty of durability testing —-I have not put it through what a soldier or SWAT unit would do on a day-to-day basis over a long period of time. However, if 10k+ rounds says anything- this weapon will likely be about as resilient as anything they are currently carrying…


    1. The gun belongs to a buddy of mine, and funny you should ask, I did get to shoot it again last weekend. It’s obscene how little recoil the gun has. I also got to shoot it suppressed, and it was by no means gassy like a lot of bullpups when suppressed. I hope you enjoy the rifle as well!


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