STA 50A .50 Caliber Fully Suppressed Semi-Auto with Hydraulic Recoil Dampening System

A small British engineering company called AEI, based at Ascot a few miles outside London, is best known for making gun barrels for aircraft and for heavy machine guns. The company has recently begun branching into small arms weapon design. At the DSEi Arms Expo in London this week they revealed one of the most interesting firearms I have seen in a while now.


The STA 50A (pictured above) is a lightweight, fully suppressed .50 BMG semi-automatic rifle designed with special forces in mind. I am told it has a novel locking system inside and that this, combined with finely tuned hydraulics and recoil springs, results in significantly reduced recoil. The company says the rifle has been designed to be fireable from the shoulder in the off hand (standing unsupported) position.

As you can see in the photos, this is a bulky rifle system, but apparently it does not weigh as much as it looks. Our spy told us that he estimated it weighed 30 lbs and suspected they are using expensive alloys to achieve this weight given the bulk of the rifle. For comparison, an unsuppressed Barrett M82 weights just under 30 lbs.


No butt stock. It appears that a simple rubber pad would be sufficient with the receiver sitting against the operator’s shoulder.

The company was not willing to reveal much more about the gun. We do know it uses a 5 round box magazine and the platform has been designed to scale up. If the .50 caliber concept works, they will produced a 20mm version, which will also be capable ot being fired offhand! Now that would be something worth seeing!


The company also had a mockup of another variant of this rifle on display. This version is named the STA50B and it uses a more complex hydraulic recoil system.  It looks like something that should be mounted on the side of a helicopter, or the front of an A-10 Thunderbolt, not shouldered!




I look forward to hearing more about this gun. AEI, if you are reading us, please invite us to a test firing!



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.


  • mikewest007

    Add an armored powered exoskeleton and it should work…

    • Matrix3692

      nah, “THE” candidate for future anti-exoskeleton rifle.

  • Giolli Joker

    1 of each and the 20mm in pre-order.
    Thank you.

  • Stephen Beat

    And you guys say we Brits don’t make interesting guns any more…Pah! 😉

    • Anonymoose

      Who says that? Accuracy International is way cooler than Remington or Barrett, imo. Also, HK is sorta kinda British (major production plant there).

      • roguetechie

        Personally I am not sure I’d be all that quick to claim HK at this point…
        And accuracy international is like Ferrari… The IDEA of their stuff is cool until you look at the price tags for even simple little items that you will have to purchase to actually have the gun you see on the magazine covers…

    • dshield55

      I’m still waiting for Enfield 2.0 rifles.

      • Stephen Beat

        Aren’t we all…Aren’t we all 🙁

  • Cytoxan Red

    I’ll buy that for a dollar…

  • spotr2

    They must be breaking the laws ….. of physics. Light-weight weapon + 50 BMG + a claim of possible off-hand shooting, do not normally seem to logically fit together.

    • Giolli Joker

      The Barrett M82 is in the same estimated weight range and can be shot off-hand, as long as the shooter has the muscles to keep it on target.

      • All the Raindrops

        I.e. Miculek

        • Giolli Joker

          Well, he’s not the only one… but definitely the only one able to hit a target 1000 yards away!

    • PK

      I believe I saw this system in a demonstration in May, 2011.

      It works very similar to the balanced recoil system, when combined
      with a strong spring type of shock absorber. The term “semi-auto” is technically
      correct, but the fastest possible cyclic rate is extremely slow due to how the two recoil systems combine to spread out the recoil impulse over a comparatively long time when larger calibers are used.

      Let me dig out my paperwork from that time period, I bet I have a photo of the prototype, the patent application number, and so on.

      • Giolli Joker

        More info would be great! Thanks!!!

        • PK

          Done, see my new post above. I hope I helped shed some light onto how this system operates.

          • Ian Jordan

            What in the world do you do that you got to see something wild like this and how do we plebeians get on your level

          • PK

            I’m a mechanical engineer who also happens to own a small firm. Due to the companies and individuals I regularly work with, I am able to attend various interesting conferences and exhibitions.

            Sadly, most aren’t open to the general public as there are quite a few presentations that require a non-disclosure to view and attend. The same goes for the live fire portion of most of these conferences.

            Luckily, the system in question had no such restrictions in any of the paperwork for that conference.

      • PK

        Alright, here it is fresh from the backup drive. Keep in mind this was over four and a half years ago, and it appears the design has matured from the pictured “proof of concept” prototype.

        You can see the counterweight on thin bars inside the receiver, the silver block straddling the barrel. This is in the full recoil position, and you can see the yellow chamber flag holding it open. When actually firing, the entire mechanism also recoils against the twin springs you see as well.

        • Very interesting, thanks.

          • PK

            You’re welcome. I’ve been enjoying your blog for a while now, and I’m happy to have been able to give something back!

  • DW

    “Small arms”

    • milesfortis

      I though the same thing – “Mortar…smallarm?” – when I was first told that the Army (before they combined the smallarms and artillery repairer MOSs into one) made the dividing line the old 4.2″ mortar. Not that it made a lot of difference beforehand as each section helped the other one when busier, hence the combination in the early ’90s.

    • PK

      As opposed to towed or self-propelled, yes. Anything man-portable is generally considered small arms.

    • noob

      if you lift it you’ll get bigger arms

  • Anomanom

    Be vewy vewy qwiet. I’m hunting dinosawrs.

  • h311r47

    I realize the mechanism (especially the magazine) is different, but it resembles a scaled-up Calico 9mm to me.

  • dshield55

    The best part about this gun is it takes AR15 pistol grips. That’s probably one of the most important features I look for when choosing which rifle I’m going to spend $10,000 on.

    • noob

      full magpul furniture by 2016.

    • MR

      That $1.97 A2 grip really sets it off nicely. Only thing better is if they would spring for the $8 Tapco “SAW” style AR grip. But seriously, an AR grip is the way to go. Easy to swap out, and already has massive aftermarket support.

  • William Johnson

    Looks like something that Briareos would carry

  • Brocus

    that’d work well on a rather small drone

  • Phil Hsueh

    Does that thing actually have a butt stock, because if it doesn’t, could it be technically DROSd as a pistol?

    • Christian Hedegaard-Schou

      It wouldn’t be a pistol, it would be a Title 1 “Other”, which is also legal in CA under the .50bmg ban. Basically, it’s legal for the same reason that an M2 is.

      • MR

        Could it be imported without the 922R hassle?

  • Alexander Nguyen

    This looks like it was designed by a teenager doodling in their lined notebook in class. It also seems like a really dumb idea. Who seriously needs a suppressed .50? It’s not like they’re shooting subsonic! I mean, it’s not like you can’t put a can on a Barrett. How is this supposed to be man-portable? It’s heavier than a Barrett and has lower ammo capacity! A Barrett really isn’t that bad recoil-wise either. This looks like possibly the worst gun ever. Lightweight, with a barrel mechanism like that? Ha good luck. If the .50 is successful they’ll make a 20mm? I will bet a lot of money that this company is going to fail very quickly. I don’t even know who they got to invest in the first place. I can’t think of any military that would dare adopt such a stupid thing that is sure to be exorbitantly expensive and prone to failure (I would also bet a lot of money that it is not reliable). Civilians, please don’t prove me wrong.

    • PK

      You do realize that AEI is primarily a MoD and DoD supplier, don’t you? This will sell just fine.

    • iksnilol

      Uh, it is about the same weight as the Barret. It only looks bulky because it is hollow for the counterweight to travel. It is shorter than the Barret and I doubt making a 10 round mag would be too hard.

      • PK

        Ah, finally! Someone else who recognizes the system. Funny how far behind public knowledge of these things lags, isn’t it? I hate NDAs.

        • iksnilol

          I’ll level with you, I only know what I know about it from you. Because you posted a pretty decent description of its workings. At least I believe it was you.

          Yeah, NDAs are pretty stupid. It’s like when somebody tells you: “I shouldn’t tell you this… so I won’t.”

          • PK

            If I could even briefly write an overview article for this website of the things which have been developed since 2004 and are only now entering public view, I would. I understand the need for the agreements, but I personally find that they slow development down.

            But, national security and all that.

          • John May

            Yeah, I remember reading an issue of small-Arms-Review back in 2009-2010 where there was a mention that Special Operations had sent out a request through FBO(Federal Business opportunities), to develop a man-Portable LETHAL power level Directed Energy rifle/Carbine…wonder what ever became of that?

          • PK

            I don’t wonder.

    • Squirreltakular

      Why would you need subsonic? The only reasons that the military uses suppressors are to a) limit noise and flash in CQC and b) to make it more difficult for the enemy to ascertain where they’re being shot at from when at distance.

      Also, the M107 is 28 lbs, which means that unless the suppressor for it is 2 lbs or less, then this system is actually lighter.

  • Ed

    With .50BMG you want it to be heavy to kill the recoil.

    • iksnilol

      No need for the weight if the recoil is spread out over a long time.

      • roguetechie

        Exactly iksinol,
        There’s a PDF floating around of the two part article fighting firearms did on the Robinson guns that makes me say what I said above.
        Even the early gun before he was sent to the UK were putting less force on the mounts than the 30 caliber brownings it was designed to replace. Also, much of what is said about the fire rate issues the Robinson guns supposedly had is incorrect.
        I’d have to get the PDF off my archive hard drive to give exact numbers, but when I finally got a copy of the articles earlier this year…
        I’ll be blunt in saying that I was downright disgusted at what is being passed off as state of the art in big bore lightweight weapons.

        • iksnilol

          What are these Robinson guns?

          Eh, we both are. The frustration is endless when people claim that the “Barred fiddy cal is the best and mostest accurate sniper rifle ever made!”.

          • roguetechie

            Russell S. Robinson designed and built everything from 50 caliber and up guns and cannons on the high side. To 30 caliber and even 9mm Para guns on the low side that all used his constant reaction concept.
            interestingly enough the reason you see zero mention in CHINN has to do with the caveat in his foreword…. The one about guns that are too valuable to allow reference of in open literature.
            Hell, the GD gun is basically a Robinson retread. Though not as good if the public literature is to be believed.
            Really Robinson got much lighter guns to that had amazingly small peak reactions to fire rates very competitive with the browning guns. (550-650 rpm in a 50 that doesn’t beat itself to death. 1100 if you just need fire rate over gun life.)
            however, I doubt you’ll see any real research into the path he took because of the NFA.

  • Christian Hedegaard-Schou

    This thing is designed to be mounted. There’s a pintle of sorts right in front of the trigger guard. You can see it in the 4th picture.

    • Giolli Joker

      That is perfect for a bipod…

  • harry

    somebody knows something we don’t

    • Squirreltakular

      What, like the mole-people are coming, and they have power armor?

  • dshield55

    So it appears to be a pullpup that is reasonably near as heavy as a Barrett. I wonder what this has that the Lynx .50cal Bullpup doesn’t.

    • iksnilol

      Integral supppressor and recoil dampener?

  • PK

    That appears to be the fabled “shoulder thing that goes up”.

  • dshield55

    This gun is so wide, it could probably be modified to take doublestack .50cal magazines.

  • Southpaw89

    Going to need to see this in action, a semi auto fifty cal fired from the shoulder would be a sight to see, not to mention the 20mm.

    • MR

      Need to get Jerry Miculek one (or two).

  • noob

    hmm if they can scale to 25mm then that means they could make it carry as much explosive payload as the XM25 Punisher Counter Defilade Target Engagement system with its airbursting projectiles, except pushed by a lot more propellant for increased range and flatter trajectory.

    might need to upgrade the electronics in the projectile to make the airburst timer accurate and robust enough to still detonate at the right position as it sails over the target’s cover.

  • jerry young

    can’t wait to see this in 20MM! it’ll be a monster

  • sliversimpson

    The ergonomics! Optimus Prime is pleased.

  • roguetechie

    Normally I’m all in favor of new technologies even when they seem very large and kinda odd for what they are…
    But I have to say that this is just sad…
    Most especially since it comes from a company in a country whose MOD has better versions of this concept in the pattern room…. Really much better, simpler, more svelte, and with the fire rate issue solved.

  • Esh325

    I think the Brits should step up their game and try to make a domestic design to replace the SA80 and C8 carbines in service,

  • Cattoo

    And PK goes silent….Nothing but crickets.

  • Cattoo

    I’m sure all that and more is developing, developed and even deployed. Gotta be ten years out what is suspected to be and what already is.

  • iksnilol

    That looks so awesome. I want one… no, mutliple ones.

    • roguetechie

      I have both full articles that represent the majority of the available information I’ve managed to chase down on the subject.
      It’s pretty sparse, but hopefully one day N.R. Parker will actually share the information he’s managed to gather freely, rather than hold onto it with both hands hoping for a payday that would’ve came already if it were going to some time in the 90’s or ought’s….
      honestly though I expect that around 2020 we’ll see another article from him or his estate….
      (is this me tossing down a gauntlet in a very public arena to try and embarrass someone into doing the right thing…. Yup you bet it is)
      It’s also me decrying the stupidity of current copyright law which allows people to buy and sell rights arbitrarily until the information itself is lost to time rather than putting a hard and fast end point on how long you can attempt to continue monetizing the same information.
      And as someone whose current and future income potential pretty much rests squarely on monetizing “intellectual property” I have a right to! All that said, while I’d like a little residual income in my dotage from work I’m doing now….. I’ll be damned if my kids or grandkids deserve a damn thing for my work!
      Those little bastards can go out and make their own names!

    • roguetechie

      All of his guns are pretty nice looking in a way.
      He also designed a very nice ring mount meant to be cheap enough and universal enough to allow supply trucks to have a functional mount for any gun they could scrounge.

      • iksnilol

        That sounds awfully practical.

        • roguetechie

          a lot of people blame Robinson for the M73/219 and M85 debacles. But if you have a Small Arms Review subscription and are set up to use their web archives you can read three different interviews from late Springfield people to GE people (the guys that wound up trying to fix the problems after the arsenal got killed by MacNamara era stuff. And you get to hear at least two sources say that when Robinson turned down their job offer they hired another firm to write a hit piece on the model 33 & “suggested fixes” to make it “acceptable”…
          Yeah, they fixed it right into never working well again. It’s funny how often Springfield seems to have done that though…
          Anyway, they turned guns that worked into crap. Dumped it on poor GE, and the rest is history.
          funny but sad, is the XM307 / 806 Both of which have pretty heavy Robinson DNA in them… And still don’t work. Karma…