SARG XS2012 Rifle

SARG XS2012 is a rifle that a TFB reader has been developing for the past couple of years. The first prototype is being put together right now, with its first live-firing in the not-to-distant future. It has a very clever gas system. The piston extends all the way to the rear of the bolt carrier, giving the gas a more space to expand and therefor decreasing the pressure on the bolt.

The term “delay” is simple in that the gas piston is affixed to the rear of the bolt carrier. The gas piston is about 6″ long, therefore in the actions full travel (around 4.8″) the piston is still inside of the gas tube preventing any excess gasses from bleeding into the chamber. The gas piston sits just slightly behind the loaded cartridge when the chamber is fully closed, theoretically eliminating barrel wobble and helping stabilize the barrel harmonics. And yes, it would be considered a long stoke gas system. It was designed to eliminate the accuracy problems abundant with long and short stroke piston systems, while keeping the Direct Impingement accuracy.

I am looking forward to seeing the first photos of this rifle.

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.


  • Terrorhase

    The Rifle is looking good. Not really my taste, but I lkie it. I hope, that the new Gas-System is working better than others (the gas system of my AR-15 is creepy, and the system from my SL8 fails very often.) By the way:

    I wanna have two of this rifles (seriously!)

  • Alexander_Degtyarev

    Accuracy problems? What?

    The location of the piston has little to do with barrel harmonics, as there is still a gastube and gasblock attached to the barrel. Those are the one influencing the harmonics. I foresee little difference there.

    I do see some small advantages here, but it’s getting overhyped, like everything these days.

    Also @Terrorhase, American SL8’s have unreliably magazines, but the gas system, unless theres something really wrong, is very, very reliable. I recommend you have it checked out. I never have issues with my European model. Got about 2500 rounds through it and not a single jam. I use the 30rd G36 magazines and the double-stack SL8 10-rounders.
    You do need to clean your piston every 1000 rounds.

    • Ian

      You’ll never convince people of this. If it resembles an AK in even the most remedial way it has to be bad.

      I love the “piston” system on this. All the *cleanliness* of a standard AR gas system with extra weight!

      Other than that, nice ugly ACR.

    • Christoph “Terrorhase”

      I´ve got the german SL8. I clean the whole rifle after every training (for normal not more than 50 shots). Although i had send the rifle to HK twice, the problems still occur.
      (btw, in a german SL8 it is impossible to use the G36-Magazines…)

  • Tyler Marcoz

    Well, it is unlikely to be any big leap in technology; the assault rifle has pretty much plateaued. But, I’ll admit, when I saw it, my first thought was “that’s real freak’n neato.”

    • Komrad

      Real freaking NATO 😉

  • TimHunterNZ

    That’s a nice looking rifle. Though I’m not entirely clear about how disconnecting the tappet is going to help – or is it indeed disconnected? Regardless, very nice. Looks a bit like an ARX-160.

    I’d also like to know what CAD software he’s using to make those. I’d love to get my hands on a copy for my own rifle project. Any ideas where I could get it?

    • 6677

      Autodesk, 3dsmax, blender, they should all do it. Hell a mate of mine managed to model a pretty damn accurate L85A1 in googlesketchup although that I wouldn’t recommend.

      • TimHunterNZ

        Yeah, tried Google SketchUp a few years ago and I wasn’t too impressed by it. Hard to even model a descent tube with the thing. I’ll have a look at the others though, thanks.

      • 6677

        Blenders the only free one of the above, and also hideously hard to use.

        Sketchup is pretty good for quick mock-ups but I wouldn’t try detail work in it, unlike my mate whos always on it.

    • gak_pdx

      The background and rendering effects look a lot like SolidWorks.

      Even if this particular guy isn’t using SolidWorks, it is basically the industry standard at this point.

      Seats start at $6k + $1k per year for the license. I have the full package and it is absolutely worth every penny and is quite reasonably priced for what it does.

      • TimHunterNZ

        That’s good to know. I’m assuming that, for the price tag, it comes built with quite a few features.

      • gak_pdx

        Well, if you are using it to design actual products, $6k is an absolute bargain for what you get. I make my living on products designed in SolidWorks, so I frankly did not bat an eye when I bought my seat, nor do I complain when I get the $2k bill per year to keep the maintenance up.

        However, if you just have an idea and you want to push it forward, $199 will get you a seat of Alibre Design, which basically does about 90% of what SolidWorks does.

        Mind you, I wouldn’t base a whole company on Alibre; SolidWorks is a lot more stable, offers a lot more tools (like mechanical simulation, FAE analysis, version controlling) and pretty much any manufacturing partner you’ll ever work with has a seat of it – at least the good ones do. BUT – for learning an idea, or bringing a concept along to show people, Alibre is a great option.

        Someone noted 3dS Max, Blender and SketchUp – those are modeling apps, not actual CAD applications. They cannot make engineering accurate models, nor do they output the sort of files a machine shop would want to work with. They are surface modelers for making graphic/animation/video type work. At that, they kick SolidWork’s butt (SolidWorks sucks at modeling organic things), but they are NOT engineering/CAD applications.

      • Nater

        What about /Pro, CATIA, and NX?

      • gak_pdx


        Between the three, only Pro/E competes against SolidWorks. I gave it a quick evaluation when I was CAD shopping, but decided against it for three reasons: The interface was awful, the price was much higher and not a single machine shop I called had a seat of it (so models would either need to be turned into stupid 2D blueprints or spit out into an interchange format like a Parasolid; I vastly prefer to just shoot someone a strait SolidWorks file).

        This was 6 years ago though, I hear Pro/E has been getting it’s ass kicked, so they have made a lot of positive changes. I don’t know how effective those changes have been as I still have yet to run into anyone who has a seat of it.

        In that same time period, Autodesk also introduced Inventor. It has some very nice looking features, it comes from a huge company (so it’ll be around for a while) and it plugs right into the entire Autodesk pipeline. Like Pro/E though, I don’t know a single shop with a seat of it though.

        CATIA and NX are in an entirely different class of CAD software, run exclusively by really big companies. CATIA is known for being *the* tool for creating hyper accurate, complex, organic surfaces and is the standard for the automotive industry. NX is known for assembly collaboration; the guy designing the radiator and the guy designing the windshield washer bottle both get to see the bounds of each other’s work as they are independently designing their systems. If you’ve ever wondered how the hell anyone could package the innards of a car or an iPhone with so many intricately fitted components, the answer is NX. At BMW, exteriors of vehicles and interiors are designed and tooled from CATIA. Engineered components are done in NX. Mind you, we’re talking $30k-$60k for a seat of this…

      • Ian

        There are a few scant companies in the arms industry using Pro/E. I weep for them. It is the most difficult software I’ve ever had the pleasure have using.

        Several use Solid Edge as a cheaper alternative to Solidworks. It’s faster to work in, but lacks some of the higher end features. It also suffers from the moronic Ribbon bar.

  • ColonelColt

    I think the idea is that you have less weight hanging on the front of the gun sitting on the barrel and that by significantly shortening the piston part of the long stroke piston system you reduce moving mass while firing. On the other hand, certain systems specifically state that the mass being over the barrel helps with recoil as the bolt carrier/piston assembly moves back into places pushing the gun down. It certainly seems to help the SCAR out during rapid fire.

    • TimHunterNZ

      I suppose that would help, less mass recoiling. Though I guess it really is give and take.

    • Doesitmatter?

      I believe what you really meant was to have operating rod/piston concentric (tubular) such as Vz52 and one German design from war time. Other than that, further out of barrel axis you are, the more tilting momentum is bulding up and that’s not really helpfull.

      On the other hand, decent amount of mass in primary parts (everything minus bolt) is of advantage. It’s essentially an “energy battery”. Many of old fashion mg’s are good example. Than of course you have to prepare beefy buffer. It’s all in tradeoff, as they say.

  • Marc

    Is excess gas cut off or bled away, or is it just pushed back through the tube into the barrel?

  • DW

    It is basically an AK action with a shorter piston and a gas tube for gas expansion

  • Sian

    Looks very G36/SL8 on the base end, which isn’t a bad thing.

    Looks like excess gas is bled out the little holes at the front of the chamber.

  • Kudos to him for moving the often slow wheel of innovation forward. I wish him the best of luck and hope he becomes a rich bastard for his hard work!

    – Damien

  • Big Daddy

    I think the Noreen Semi-Auto long range rifle in .338 Lapua uses a similar gas system.

    They say the piston is in the receiver. That sounds a lot like this setup and it makes sense to me.

    It would be lighter and you would have kind of the best of both worlds.

    But I wonder about cleaning, does the gas tube get very dirty? I would think so. Does it need more gas to make it work, or is the hole for the gas closer to the chamber? Does this have an affect on recoil? I have a lot of questions.

  • bob

    Good luck to him! I hope he pulls it off and gets a company going. For his sake I hope he is U.S. based or is going to be as this would be the friendliest environment(minus CA) for sart-up firearms company in terms of regulations/manufacture and civilian high demand. For a western firearms company to stay in business our U.S. civilian market makes most of the western gun companies profitable, that’s just a simple fact of having a main stream gun culture of 90+ million civilian gunowners. The number one client of colt, s&w, ruger, beretta, cz, hk, fn, walther, etc. is the U.S. civilian market. You don’t sell to us you won’t stay in business for long unless your state-owned/subsidized.

  • Mike Knox

    Whoever did this ought to have a patent before publication..

    • Tyler

      This design has multiple patents pending on it. Any aditional information could be found at

      • Marebear

        Very good information. I like the product. Thank you!

      • Doesitmatter?

        Yesssereee…. I looked at that and…. what I see is not an humble cash-strapped tinkertoy, but a fair looking gentleman with ‘scala’ of business-accesory females, not older than 35. Very professional indeed. So, what does it say? We are dealing with Mister Somebody here. Definitely not a small potato. So let’s be ready!

  • Tinkerer

    Interesting idea. I get flashbacks of the Ljungman AG-42 rifle.

    • Likvid

      Exactly my thought. I’m not really sure if we should call it long stroke piston system, as I think it’s closer to Ljungman DI system, rather than anything else.

      • buster Charlie

        I thought the same thing. A while back I saw some people cut the ak gas piston down all the way to the carrier nose, and the gun still functioned. I reasoned that if a super short ak carrier worked with a short barrel, the same carrier should work with a long barrel if you used an ar15 style gas tube to feed gas into the same shorty gas system. call it a hybrid Di/long stroke.

        Then I discovered many guns essentially did the same thing. the ag-42 as mentioned, to some degree the mas 49 autoloader. the hac7 rifle uses a longer piston, but has a gas tube extension. then I noticed the Israeli Tavor used the same length gas piston for all barrel lengths, and used a gas tube extension to reach the longer barrels gas ports.

        so unless I’m mistaken, there is prior art all over the place in regards to having a long thin gas tube transition into a long stroke gas system with a short piston.

        really,I thought I was rather clever for thinking of it, but soon learned its not a new idea after all.I do like how the Tavor uses it to allow multiple barrels to be used without changing out the gas system.

  • Vhyrus

    Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39 Make it in 7.62×39…

  • Doesitmatter?

    It’s tough to present real innovation, besides there must be real reason for the way things are done. Couple points to consider:

    1. Change in “harmonics” for benefit of accuracy – I doubt it. This design appears to be ‘stretched out’ instead to be compacted aroud mass of barrel. That is not exactly helpful for vibration pattern and resulting accuracy. Perharps you can add solid clamp between both – but this will add weight.
    2. Every reliable system must be initially overpowered to work reliably at adversed conditions, so forget ‘softer action’. It will not happen it you should have enough power al the time. I do not see any means of regulation.
    3. Cleaning the ‘trompet’ – this is big one. I have plenty of experience with carbon filled gas chambre, no fun to clean unless you have free access from both sides (e.g. removable plug in front). M16/ C7 (in Canada) is delivered with cleaning swabs…. not much to add.
    4. Finding customer…. well, good luck! In this world there is already way too many rifles. All look one way or the other much alike; real innovation still missing.

    In any case, I command the creator for his ingenuity and courage to open self to critique. It may help; this is in companies called customarily “the design review”, before metal is cut. What is most telling is real world test. Try it, do it and tell us more!

  • MAX


  • PCP

    It’s pretty much the exact opposite of what FN did with gas system of the SCAR, a light weight long stroke piston where all the action happens near the bolt carrier (and the SCAR being a short stroke system with and oversized carrier and a mini piston). It’s interesting and sound, but accuracy depends on a lot more (match grade everything) than just gas system configurations, and it still has a long gas tube to clean… not I deal breaker to me. Let’s hope this one succeed.

  • Whatever

    “The gas piston is about 6″ long, therefore in the actions full travel (around 4.8″) the piston is still inside of the gas tube preventing any excess gasses from bleeding into the chamber.”

    Tight tolerances to keep gas from escaping mean it takes very little fouling to gum up the works. Also if it isn’t aligned properly, it’ll jam.

  • ColonelColt

    To those who think the bolt system looks like a G36/SCAR, etc. you would be right- Since most modern rifles are based on either the AK-47’s or AR-18’s bolt system in some way. It’s pretty simple: Big block of steel with simple machining to place the rotary bolt inside. I guess the idea of a simple bolt system that can be manufactured in a standard machine shop easily is finally winning out over the AR-15’s style of bolt, at least as far as number of designs using it.

    I’m actually curious as to what material is meant to be used for the gas tube/piston cylinder. It kind of looks like some sort of stainless or titanium alloy by the shape. I’m also wondering why it doesn’t simply vent after picking up enough inertia to cycle the action. If the piston remains inside of the piston tub through the whole cycle that means that all of the carbon buildup has nowhere to escape to. If the piston is a tight fit it *could* be self cleaning if lubricated well but at the same time it would be more likely to lose velocity with heavy carbon fouling. The tube does appear to have four tiny vent holes but that’s not going to allow fouling to escape like in an AK’s piston system.

  • Esh325

    I’m not an engineer or gunsmith, but I think this is an answer to a problem that doesn’t exist. Since when are there accuracy problems with long stroke piston rifles? Every Sig 550 made is required to get a 4.3 in group at 300m’s! To my knowledge, there is no set standard for how accurate a combat rifle is suppose to be. Every country has their own idea of how accurate a rifle should be. And let’s pretend for a second that long stroke pistons are not accurate enough, but there is more than one way to accurize a firearm. The improvements in barrel technology and ammo cannot be denied. I don’t want to sound like I’m poo pooing all over his idea, I do commend him for creating his own design. I’d like to see him make an actual firearm then we will see if it provides significant improvement over existing designs.

    • RedRalph!

      Perhaps you havent seen a high speed video of an ak being fired..

      All firearms will have “barrel wobble” to an extent, however piston guns it’s a little greater. If this gun gives 1″ better in accuaracy @ 300 meters, it’s well worth the effort IMO.

      • Todd

        Compare a DI gun and a Short stroke and im sure at 300 yards there will be a small difference in accuracy

      • Whatever

        An AK could be made that would shoot 1 MOA, it would just have to have very tight tolerances (very little clearance between the moving parts) plus a quality barrel and quality ammo. That would also cut down on its reliability as the loose tolerances in production AKs are what make them reliable and inexpensive to produce.

    • W

      SIGs are astonishingly accurate for a long stroke piston rifle. 🙂 Everybody seems to bash the AK for its accuracy, or lack thereof, particularly with the warping of the barrel because of the violence of the action, though one must consider it is a assault rifle, meant for that 100-300 meter engagement range not a precision rifle or DMR.

  • Vitor

    There are so many piston guns that are quite accurate. As Esh pointed out, the swiss army demands more accuracy of their long stroke SIGs than the US army demands if their DI M16.

  • Esh325

    The AK is only one example though.

  • shockfish08

    Hmmm, looks allot like what Al Zitta (ZM Weapons) did with his LR300 series of carbines and rifles. Except this is still a piston system wheras the LR’s used a closed-off DI system.

    • Solomon

      DI when it’s Stoner’s DI is still a piston system. The bolt is the piston, so obviously it gets dirty like any other piston.

  • spartan_b88

    It looks like there is going to be a ridiculous difference between the bore and the sights. It might be the pictures though.

  • I commend the designer for his industrious spirit. It’s good to see people putting out the effort and trying to think of new ideas. This design has been done at least twice. The basic concept was used on an older AK type rifle, maybe an Egyptian rifle, I can’t remember the name. It used a gas tube straight back and the gas acted directly on the front of the bolt carrier, which had been extended forward over the barrel slightly ala SCAR but not as far forward. That’s basically what was done here. The piston is simply an extension of the bolt carrier.

    Secondly, I tried this design in the Massoud rifle while working for Magpul. It looked nearly identical except the gas tube didn’t rebate into the carrier. It wasn’t the best system for several reasons and I ditched it for a system we ended up patenting.

    It is nearly impossible to seal the piston to tube fit, especially in a system like this where you have a moving bolt carrier which must have a certain amount of play in all directions. Also, high speed video shows that gas will blow right by piston rings before there is even much movement of the carrier. That’s not a problem for function, only for cleanliness.

    Also, gas leaking into the chamber and fouling the chamber has never really been an issue for either DI or piston guns (except when running a supressor), perhaps there was something lost in the exchange. Maybe he means action area. At any rate, fouling in the action on this design will likely be less than an AR but the fouling will collect inside the bolt carrier, where the gas exits the tube and does a U-turn to come out the front of the carrier. Some gas will escape out those small holes and keep the fouling out of the action area.

    It looks like a good effort and it is no small feat to develop an entire firearm, even one that borrows from previous designs like the AR-15/18. Unless your company is extremely well funded I would caution against trying to bring this to actual production, but Great job!

    • bob

      Justin J, excellent insightful comment! As an owner of a Bushmaster ACR, I see the high potential of the design and even in its “Remington” form I like a lot of things about it. I wish magpul would have had the financial resources to continuously design the rifle to its fullest potential, that would have made it my all time favorite platform. On another note whats with the “thumbs down” person? Born with a stick up your butt, uncapable to process an intelligent insight?

  • Why continue to use the AR-15 type bolt, which may eventually have lugs break off? Why not use few larger lugs?

    • Solomon

      Stoner bolt with many lugs means the area the bolt locks into can be *much* smaller. Khalashnikov or other style of bolt will require a *massive* barrel extension, or for the lugs to lock into the receiver, both of which will complicate things further and/or add large amounts of weight.

      • The Robinson XCR uses a sort-of Kalashnikov-style bolt, and they are not terribly heavy.

        • Solomon

          The XCR was deliberately meant to mimic/improve on the AK design, this is not. The weight adds up. The XCRs are not terribly heavy, but they’re still heavier than they could be for what they are. The XCR pattern could be considerably lighter by going with a Stoner pattern bolt/locking area, and a HAC-7/Tavor concept gas system where a “DI” style gas tube brings the gas back to an extremely short piston.

          There’s “not too heavy to use,” and then there’s “too heavy to pay for”. A lighter rifle is always better unless it’s a bench gun, and as long as you’re not worrying about lugs breaking, there’s no reason to make the rifle heavier by going with a Kalashnikov bolt. The Israelis went with a Kalashnikov bolt for a very obvious reasons… they don’t intend to maintain their weapons in any regular fashion(have you seen those beat to hell AR-15s?). Most other countries that have more money to spend on the smaller details of their military is going with a Stoner bolt. Any half-decent AR-15 bolt will run at least 10,000 rounds before you should really be checking it for stress marks, and 10K rounds is probably at least a couple or a few thousand dollars, depending on what you shot. A half decent bolt should be used for 15,000 rounds before replacement for safety.

          If you can afford to shoot 10 or 15,000 rounds(and you probably won’t need to replace the bolt, anyway), you can afford 100 bucks, or 200 bucks for a replacement bolt.

          LMT makes an electroless nickel plated bolt which is supposed to outlast most everything else out there, and their center lug opposite the extractor is structurally compromised, so 10 or 20k rounds after you start on it, the first lug to sheer will be that one, and it will never be a catastrophic failure, since the load will be distributed evenly.

  • Esh325

    Why does it have to be an AK though? I just mentioned the Sig 550.

  • For great prices on tactical gear, check out