Rock River Arms PDS Pistol

The new RRA PDS Pistol is the first firearm from RRA to utilized their new PDS pistol system. It features a full length picatinny rail, two position gas regulator and non-reciprocating foldable ambidextrous charging handles. The PDS system must have a return spring either under or around (telescoping) the barrel. No buffer tube is required.

Caliber 5.56mm NATO and .223 Rem.
Barrel 8” Chrome Moly, 1:9 twist
Overall Length 17.5”
Weight 5 lbs
MSRP (Price) $1,335

A carbine version is coming soon.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • SpudGun

    It looks very funky but as always with these types of configurations – what’s it for?

  • ap

    I know everybody says these things are worthless but add a folding stock and tax stamp, and wouldn’t you have a somewhat practical SBR PDW?

  • gunslinger

    so the spring is around the barrel and the BCG “pulls/extends” the spring once a round fired and the spring will then “pull/compress” bringing the BCG forward to chamber a new round. is this what is going on? like how many handguns operate, this one is all internal and we don’t see a moving slide?

  • Redchrome

    This is one of the things the AR15 has needed for a long time. (Tho let’s face it, the AR18 basically did the same thing in the 1960s, only better in some ways).

    If the recoil spring is wrapped around the piston, the problem there is that the spring will get hot from the gas & conduction from the barrel, and will lose its temper.

    Still, give it a folding stock and a 16″ barrel and it’ll be pretty cool. Like a Para TTR, but with the charging handle in a sensible location.

    I wonder if the charging handle has a built-in forward assist?

  • Don


    Is this kind of weapon meant to fill a CQB role similar to the role of something like an MP5?

    If so what are the popular arguments for/against 5.56mm in these roles?


  • I’m just waiting for one of those companies to put rails on the grips, so an operator can attach grips to the grips.

  • Nanban Jim

    I just love these extreme technicality “pistols.”

  • Adam

    Why does it always seem like when I dream up a sweet new firearms idea, a week later a company builds it. I swear they are spying on my thoughts #tinfoilhat

  • DougF

    Does someone make a folding stock which mounts to a MS1913 rail (such as the rear facing accessory rail on this new PDS)?

  • Kurgen99


  • Seriously only $1,335? Nice.

  • TR34

    This looks like the first gas piston ar-15 someone actually put some engineering effert into. If you look at an ar-15 its apparent that the gun was just not designed to work with a gas piston. Most ar-15 gas pistons seem like a bad idea but this one looks really nice, I especially like the charging handle.

  • 6677

    give it a beta-c 100 round mag and stick it on an M16 lower

  • Vitor

    It would be really cool in 6.8mm, since it’s a cartridge that performs quite well from short barrels.

  • subase

    Basically an upgraded ‘pistol’ a more powerful MP5K which is meant to be used with a sling. The 5.56 suffers from velocity loss meaning you might as well go with a AK pistol or other caliber. The blast from such short barrels is also awesome and only of real use to the very experienced.

    It’s main deficiency is that it’s not really concealable, the single greatest advantage of a pistol. Which kind of defeats the purpose of having it.

    Still, wack on a red dot pistol optic, 20 magazine with hollowpoints and very very good flash hider. (phantom, vortex) And you’ll have some armour defeating fire power in your hands. An AK pistol is a better choice though.

  • Nadnerbus

    “Still, give it a folding stock and a 16″ barrel and it’ll be pretty cool. Like a Para TTR, but with the charging handle in a sensible location.”

    That’s what I thought when I first saw this a while ago. I don’t have much use for a “pistol” of this sort, but give it a longer barrel, and a side folding stock, and this would be a serious contender in the post-AR15 tactical market. Assuming it works as advertised.

    I wonder what the deletion of the buffer tube does to recoil. I imagine this kicks a bit more. Still, just a .223.

  • drewogatory

    I just feel that it’s poor engineering to produce a firearm that cannot utilize the capabilities of its’ cartridge efficiently. You’re just turning all that powder into muzzle flash not velocity, then you’re stuck with a 62 grain projectile. Might be better chambered in .458 SoCom or .50 Beowulf or maybe some crazy JD Jones subsonic number. Big heavy and slow works for me at close range.

  • I have to image that it’s like the Olympic Arms OA93/OA96/OA98 series, with the recoil spring, or I guess rather a return spring like you said, over the barrel and into the top of the upper receiver.

    If you poke around on the internet, you should find copies of the Olympic Arms owners manuals, which show how their system works.

    As far as practicality. . . I’m not sure how much the velocity difference would make inside structures. I’m seeing SWAT and entry teams going with short barreled AR variants. There’s also the Mk.18 in U.S. Military service, with a 10 1/2 barrel.

  • Pete Sheppard

    The only practicality these “pistols” have is recreational shooting and burning up ammo. Conversion to SBRs is a different flavor, though. Now that the state of Alabama has lifted its ban on SBRs, I’m interested. !f you like them, enjoy them! Safely and responsibly, of course.

    The makers of the “pistols” also did shooters a grave disservice by giving BATFE an excuse to ban cheap imported rifle ammo. The ammo in 5.56 and 7.62×39 had steel-core bullets which was perfectly legal for rifles. When BATFE found out about the “pistols”, they promptly banned the ammo as “armor-piercing handgun ammunition”.×39.html

  • Mada

    Adam: “Why does it always seem like when I dream up a sweet new firearms idea, a week later a company builds it. I swear they are spying on my thoughts #tinfoilhat”

    It’s the other way around. #For real.

  • Kel Tec makes something very comparable, piston driven, for half the price.

  • Looks like they will start shipping in October.


  • G3Ken

    The only thing it’s got going for it is that it looks like a lot of fun. No buffer, so recoil’s altered. My 16″ AR without flash hider (illegal in NY) already throws out a major league fireball. I’d bet you could do some welding with the flame that comes out of this thing. Then you’ve got the loss of velocity, which is already an issue on the M4, only magnified with the tiny barrel. Lastly, no sights. Adding flip-ups or holo sights only makes the gun bigger.

    I would like to put some rounds through it because, like I said, it just looks like a real pisser to shoot. From a practical standpoint, either buy a real pistol, an SBR or a rifle. Hell, buy all of them, but skip this one unless you’ve got $1300+ burning a hole in your pocket.

  • Don

    Has anyone taken the time to chrono the 8″ barrel on this PDS?

    Kel-tec advertises a 2600 fpm muzzle velocity from their 9.2″ barrel on the PLR-16 which sounds a little fast to me.

    I realize that half the fun of a “blog” site is boasting your opinion but I’m not really interested in opinion here, just factual test data, if you’ve taken the time to do an unbiased chrono on various ammo.


  • Joe Blow

    Any word on how these are holding up? For round count to part wear?

    Along with How picky are they when it comes to various ammo since they said they were designed for silencers at this point… Kinda sem odd to regulate the gass especially if you are not having the suppressor option. gets a bit vague on their catalog/website page about the model and that feature.

    Any creative uses for that small tear drop shape section of rail piece on the rear that mounts/covers where the buffer would have gone, if they had an opening large enough to mount options instead of their special hinge.

    Paying extra for the full rails for the forward in wise move between the models I have see for ability to space things out and have hand room.