Ultra-Light Sub-9lbs X-LMG Introduced by Knight’s Armament

Knight’s Armament Company has announced a new very light weight belt fed light machine gun – which they have appropriately termed the Stoner X-LMG (for “Extra Light Machine Gun). The new weapon is based on the previous Knight’s LMG, itself a development of the ARES, Inc (unrelated to ARES Defense, now called FightLite Industries) Stoner 86 LMG which itself descended from the famous Stoner 63 Light Machine Gun. Like those weapons, the new Stoner X-LMG is a 5.56mm caliber weapon, but unlike those it achieves a virtually unheard of light weight of just 8.6 pounds, unloaded. The release of the X-LMG was announced via IHS Jane’s, as well as – oddly enough – Turkish gear outlet Öztekin. From IHS Jane’s:

Knight’s Armament Company (KAC) has developed a new version of its Stoner 63 machine gun – the Stoner Extra – Light machine gun (X-LMG).

The X-LMG has been optimised for use primarily with special forces users. The unique design of operating mechanism and in-line butt-stock configuration significantly reduce firing forces on the operator making the gun very controllable, particularly during repetitive long suppressive bursts.While meeting the operational needs of the user at the time, the Mark 23 was acknowledged to be only marginally robust in use. The later Knights Armament Company redesign of the Mark 23 (KAC Stoner LMG) addressed the shortcomings of the earlier design, and has now been further enhanced with the introduction of the X-LMG.

The combination of MIL-STD-1913 rails located on the top and bottom, and side ‘M-Lok slots provide a facility to mount a variety of daylight optics and night vision devices, singly or in tandem. In addition, a further length of integral MIL-STD-1913 sight rail is located on top of the rear-receiver.

The 5.56 x 45 mm calibre weapon weighs 3.9 kg and measures 890 mm in length, including a 381 mm barrel.

Of note is the fact that the new Stoner X-LMG dispenses with the KeyMod attachment points of its predecessor and replaces them with a triple row of M-LOK slots on each side. This is in keeping with the industry’s flight away from KeyMod and towards the stronger and more robust M-LOK.

The light weight of the X-LMG puts it in the same category as other very light weight support weapons such as the USMC’s M27 IAR and ArmWest’s MGX, both of which are magazine-fed. The X-LMG has an interesting relationship between the MGX, as both weapons are the brainchildren of people who worked at Armalite during the development of the AR-15. The Stoner 86 – upon which the X-LMG is largely based – was designed by Eugene Stoner who designed the AR-10, while the MGX was designed by L. James Sullivan, who together with Robert Fremont designed the AR-15, and who was a member of Stoner’s design team for the AR-10.

EDIT: Sources tell us the name for this weapon may be “LAMG”, not X-LMG.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


  • Major Tom

    How does it stand up to the LSAT/CTSAS LMG? Comparable? Heavier? Lighter? I don’t remember the weight of the LSAT off the top of my head.

    • Petto

      LSAT empty is 9.8 lb which is still heavier than X-LMG

      • JumpIf NotZero

        You’d have to look at the loaded weights in this comparison.

      • randomswede

        The LSAT functional prototype is heavier. This is also a prototype, but based around conventional ammunition and a mature action, it’s probably not going to change much in weight.
        If there ever are any weapons put into mass production that uses the CT rounds it’s likely they’ll be close in weight with lighter and/or more potent ammunition.

        • noob

          The LSAT team did mention in a TFB interview that they did loads of Finite Element Analysis to try shave of as much unnecessary weight as possible. If you want it lighter, I guess you could reduce the safety factor a little and then shave off some more.

          • randomswede

            Well, they are likely to refine the safety factor(s) if they go into production. With prototype ammunition I would assume they added a safety margin to the safety factor.
            I guess what I wanted said is that it’s an apples to oranges kind of comparison especially when keeping in mind that the LSAT LMG is pretty much a byproduct of the ammunition research project and they weren’t looking for a new cartridge they were looking for a new type of ammunition.
            Now that they have settled on a type they are testing calibers to figure out what the cartridge should be and from there weapons can be developed.

    • Kinetics

      Well you totally loose ammo compatibility with all other weapons with the LSAT so there’s strike #1 for LSAT.

  • Denny

    As I see it the key point will come down to competition between box magazine vs. belt feed, granted capabilities are otherwise very similar or same. One consideration above others is how soon/ fast you want to run out of ammunition with belt fed weapon. Also, belt fed weapon will be more costly to make than mag fed.

    • Given that the M27 is being retailed for $3,000, it’s not like magazine fed is offering an extensive cost savings.

  • Joe

    It has the MCR beat by 1 pound.

    What’s the MSRP?

  • Ευστάθιος Παλαιολόγος

    ” very light weight support weapons such as the USMC’s M27 IAR ”

    I think calling the M-27 anything else than a regular rifle is not correct.
    I know the Marines call it an Automatic Rifle but all the rest of the world that uses the HK416 calls it a plain rifle

    • NMhunter1371

      Marine Corps issued M4’s and M16’s are select fire but only have semi-automatic and 3 round burst… The IAR is the fleet’s only true automatic rifle, with the exception of a handful of M4a1’s which I believe are only issued to recon.

      • Anomanom

        That’s as may be, but it’s still just an ordinary automatic rifle anywhere else. And I’m not pointing any fingers here, any automatic rifle is capable of 3 round bursts if you can work a trigger finger and, you know, count.

    • Correct. The M27 is a Assault Rifle with a bipod, not an Automatic Rifle.

      An automatic rifle is either a purpose built machine gun fed from magazines (BAR, Ultimax 100, Armwest MGX) or a Assault Rifle that has been extensively upgraded for use as a machine gun (AUG HBAR LMG, RPK, SCAR HAMR.)

      The M27 is just a H416 with a bipod – and is primarily used as a DMR in semi auto.

      • William Elliott

        doesn’t it also fire from the open bolt when it gets hot enough?

        • No, that’s the SCAR HAMR that has that awesome feature.

          The M27 is just a regular HK 416 with a bipod – it has no additional features to optimize it for use as an Automatic Rifle.

          Does the 416 outperform the M4/M16 in full auto – yes, primarily due to the heavier barrel and piston system letting the weapon fire longer before over heating.

          But does the M27 do anything that a regular 416 Assault Rifle can’t? No – its the same rifle but with a bipod. Which means the M27 is an Assault Rifle like the HK416 is, and not an Automatic Rifle.

    • noob

      by the same token, a Crossover SUV is a 2wd station wagon with a higher driving position.

  • Dan

    That’s smart of them to put a 1st gen Slidefire stock on it. SOCOM will only have to get one stamp (for the silencer) rather than two. I’ve been trying to rig one up on my Robinson M96. Maybe it’s backward compatible.

    • Alex A.

      😂 good one!

  • insider

    They’ve been teasing this piece of vaporware for years. It was announced at SHOT 2016 in the same configuration, and even covered then on TFB by the same author. How is this news?

    Build it or shut up about it. Knight’s has the resources.

    • civilianaf

      It takes considerable resources to bring something new to market. It is not uncommon to take 2 years to complete T&E. People watch American Chopper and think you go to the CNC and type in #smileyfacemakegoodparts and press the green button and good parts fall out of the machine. Its an incredible gauntlet to do a good job bringing something to market, even harder when its a new product.

      • insider

        I’m well aware of what it takes and they have beyond considerable resources. The KAC LMG has been “in T&E” for decades.

        • civilianaf

          Agreed, but I give them a pass. They may have had resources 10 years ago, but the market has changed since then. They have been bleeding to get this to where it is, no doubt those resources have been whittled away at for years getting this here. I give them a pass.

    • NMhunter1371

      8.6 pound belt feds are worth getting excited for…

    • Raven

      It exists, they’re just not putting it into production without a buyer, and so far nobody’s interested.

      • insider

        Build it and they will come… that’s if it’s half as good as they say it is. Same excuse as their PDW and SR47.

  • Brett baker

    Can’t wait for the LMG shoot-out video!

  • civilianaf

    Well hats off to the, congrats on doing something new and cutting edge, that is really missing in the current market. Looks well executed and thought out, and solves a problem companies have been working on for decades.

  • SP mclaughlin

    Well, at least they got rid of that horrid industrial shelving handguard.

  • PK

    If only they’d release a civilian version of this sort of gun… super lightweight LMGs are few and far between, anything sub-10lb for a belt fed is amazing.

  • Joshua

    Please replace the SAW, please!!!!

    • Uniform223

      Replacing the SAW with something like this would be a step in the right direction and would also be a hell of a lot smarter than USMC’s love affair with the M27.

      • mig1nc

        A lot of people still think the M27 was a backdoor way to get the HK416 into general use. So far, it seems like their plan may be working (if that was indeed the plan).

      • mig1nc

        And yes, I do agree.

  • Michael Powers

    something else my government won’t let me own….

  • Gus Butts

    You guys don’t understand. I NEED this.

  • feetpiece _

    Paging Dugan Ashley…

  • El Duderino

    Who you callin’ a KAC Stoner?

  • Blake

    I am seriously losing respect and trust in TFB every single day. I’m not going to rehash other issues, but this one is a perfect example of why. Every single time a weapon/item is released with Keymod, the quote is “aw they should have used M-Lok”. When an M-Lok item is announced, it’s “keeping with the industry’s flight away from KeyMod” even though they both come out in just about equal regularity. Are you guys so blind that you completely ignore all the new Keymod items and only see the M-Lok items? Really?

    • tazman66gt

      Magpul has spent a lot of money to keep keymod off of rifles. Just like they spent a lot of money during the SHOT show telling everyone they could that Keymod wasn’t going to be open source anymore but Magpul has this new product that is open source.

    • Physic

      Stop crying, “Keymod is dead, and we killed it” _Nietzsche

      Mlock is just de facto better, lighter, stronger, cheaper to manufacture, no cheesegrater edges.

      • Blake

        It’s amazing that you can write but not be able to read. But I’ll still respond even though it had absolutely nothing to do with my comment.

        That’s funny, because all 3 different FFLs I do IT work for sell ~75% Keymod to ~25% M-Lok. That’s such a strange death! Plus, what simple-minded folk like you can’t comprehend is that once a certain strength is reached people care more about aesthetics than “hurr durr but I can hang an F150 off of my M-Lok attachments and they won’t break!!11!” There are always going to be people that can’t stand the look of M-Lok. Keymod is not going to die. It’s so strange how all around us we see multiple companies offering different products and somehow they still manage to stay afloat! It’s almost like different people have different preferences… so strange.

  • Blurb

    I’m confused. Where does one make cheek weld on this otherwise beautiful baby?

    • gunsandrockets

      Stock shown in collapsed position?

      • Aaron

        Collapsed and slotted to fit around that raised optic rail.

        • Blurb

          I can’t even grow a decent beard and that sounds painful.

      • noob

        can you fit spade grips and sit behind it on a tripod?

  • Congo Rick

    Am I the only one who thinks it’s really f*cking weird that a brand new KAC product is announced via a second hand Turkish arms and equipment distributor that doesn’t even have a proper website?
    How does that happen?
    What does this mean?
    I have so many questions!

    • noob


    • It could simply mean that they copied Jane’s online article.

  • Uniform223

    KAC’s LMG has been an ever evolving process.

  • Dude

    Guys even if the weight is good, its only a 381mm/15inch barrel!

    • CommonSense23

      Your point being? Adding extra barrel isn’t hard. And the MK46 barrel isn’t much bigger.

  • LazyReader

    8.6 pounds, less bet on it’s durability as this thing rattles apart slowly. Wanna test this thing……livestream 50,000 rounds through this thing.

  • RazorHawk

    Definitely a game changer, too bad civilians can’t own these.

  • malachi13

    How the US ended up with the M249/Minimi is beyond me, especially when they had a gun like this just staring them at the face and made and designed in the US too. Another missed opportunity was the Ultimax 100.

    The SEAL teams had already proved these LMGs could swing with them, why did they not just focus on these, develop them further and gotten to the X-LMG/LAMG earlier?