Cobalt Kinetics and MARS Team Up on New Army Machine Gun Entry

This, or something like it, could be the next infantry rifle for the Army. (Photo: MARS/C.K.)

Cobalt Kinetics and MARS Inc. of Montana have paired up to develop a new machine gun for future military trials. Right now the U.S. Army is looking for a lighter and more effective machine gun than their current light machine guns.

The two main considerations for both the NGSW, or Next-Generation Squad Weapon, and are weight and effective range. Called the MARS Rifle, for now, the MARS-designed and Cobalt-built rifle promises to excel on both fronts.

“I can’t think of a better collaboration in this industry,” said MARS president Michael Merino. “Our MARS rifle design, coupled with the innovative approach to rifle manufacturing of the Cobalt Kinetics team, has been incredible.

“We believe that we have a rifle design that meets the requirements of the Army’s ambitious NGSW program. We are excited to be part of the evolution of military effectiveness. We also plan to release a commercially available version of this rifle, in the first few months of 2020.”

Due to cartridge requirements, this design looks familiar but it uses a very different system. (Photo: MARS/C.K.)

Externally the NGSW-hopeful looks like an AR-pattern rifle similar to the M4 and M16 carbines and rifles in service today. But the design varies fundamentally and uses a completely different action, along with a new cartridge and new magazines.

The Army is trying a new 6.8mm cartridge that operates in the Short Magnum range, pushing a 140-grain bullet at 3,200 feet per second, out of 14-inch barrels and shorter. It’s safe to assume this is a very high-pressure cartridge.

“The initial call-out for the program seeks to dramatically increase the terminal power and effective distance of the 5.56 and even 7.62 NATO,” said Cobalt. “The performance of the new cartridge will rival the exterior and terminal ballistics of some current commercial magnum hunting cartridges. It seems a worthwhile endeavor to outfit each soldier with an 8-pound rifle that can hit a 1 MOA hardened target and penetrate that target up to and exceeding 1,000 yards.”

The companies have submitted two designs for trials, a “rifle” version with a 13-inch barrel and a “squad” model with an 18-inch barrel.

It fires a very high-pressure 6.8mm cartridge (right), especially compared to 5.56 and 7.62 NATO (left, center). (Photo: MARS/C.K.)

To manage such high pressures the MARS rifle uses a “shifted pulse recoil” action based on the long-recoil operating system. Like a long-action recoil system, the bolt and the barrel stay locked together for the full length of the stroke to the rear of the action when firing a round.

Once the barrel and bolt cycle all the way back, the bolt locks to the rear and the barrel springs forward back into the firing position, pulling off the spent case. Then the bolt can close, ejecting the used case and feeding a new round in the chamber before locking into place.

The long-action recoil system was popular in the early years of machine gun design. Its main advantage is that it’s strong. The case and case head of the cartridge are fully supported for the entire duration of the firing portion of the firing cycle.

It’s a slow recoiling system which also means that extraction and ejection don’t have to be particularly violent, a problem with high-pressure automatics that can lead to case head separation and other jams. And because the entire barrel moves off the spent case after recoiling, the system has a lot of strong primary extraction.

If this new 6.8mm round is as hot as they claim, a conventional gas-powered operating system really might not be the best system for the job. There is one claim that does stick out about the MARS rifle and that’s accuracy.

See Also: Cobalt Kinetics Debuts Forged Upper Conversion Kit ‘Featureless’ AR Lower (50-State Legal)

MARS implies that their design is capable of shooting 1 MOA or minute of angle groups, and that level of accuracy is difficult even for conventional self-loading rifle designs, let alone military-grade guns. This is even harder with recoil-operating guns.

Because the barrel has to move — and with long-recoil, move the entire length of the action — it means it has to be free to move, as in, not fixed rigidly in place. That means that not only is the whole barrel loosely retained while firing, it also means that it can return to a slightly different position after every shot.

It will be interesting to see if this design is that accurate, and if so, how did they pull that off? The world may not have to wait for the military trials to continue, which is good because these kinds of trial with lofty goals don’t always wind up ending where they expect to go from the start.

MARS and Cobalt hope to have commercial rifles in production by next year.

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About the author: Max Slowik is a writer with over a dozen years of experience and is a lifelong shooter. He has unwavering support for the Second Amendment and the human right to self-defense. His ambition is to follow Thomas Paine, as a journalist by profession and a propagandist by inclination.

{ 55 comments… add one }
  • Melvin Pinkney September 13, 2019, 8:32 am

    At least everyone knows a problem exist. And are thinking of ways to help our troops. Just get it right. Our adversaries have been arming up for the last 20 years

  • Pantexan September 3, 2019, 7:22 pm
  • kenbay2020 September 2, 2019, 7:04 pm

    Isn’t this 6.8 round a bit over powered for the average soldier. The whole reason they went to 5.56 was so soldiers could have a light carbine with a larger mag capacity that was effective at close/medium range. The 5.56 fits this role perfectly still. This 6.8 round here is enormous. Don’t think it would work at all unless to be another sniper round.

  • GaDawg August 31, 2019, 12:31 pm

    Ammunition manufacturers would have to go to a greater expense to re-tool their production lines for a larger bullet. I wish there was consideration to the FN 5.7×28mm which has a 93 grain bullet and proven track record in militaries around the world. NATO testing found that the 5.7 could be manufactured on existing production lines thus reducing its cost.

    • Rane September 1, 2019, 6:24 pm

      Using the 5.7×28 cartridge would be a step backwards in terms of performance. I agree it’s a good round for it’s intended purpose. Which is a close quarters soft armor defeating round that fits in small carbines and pistols. It’s not even close to 5.56 power levels and they’re attempting to find a cartridge that’s more capable than it is. Retooling their bullet manufacturing is the least of their concerns. It’s an entirely different weapon with completely different parts from the last platform. So a complete restructuring of the weapons and ammo facilities are already planned for.

  • Ringo Lapua August 31, 2019, 11:54 am

    Resembles the cartridge of a .270 WSM and seems a bit more powerful. Could me the next best combat rifle if designed right. Check out the new, much faster but lighter copper rounds such as Underwood has been selling for pistols. With the right technology and improved barrels, rifle ammo could be developed that is lighter, easy to carry more rounds and much harder hitting. Perhaps then they would not need such a fat heavier round to replace the 5.56.

  • Josh August 31, 2019, 9:06 am

    So in other words, they’re virtually re-inventing 264 Win Mag….

  • Bill Hayes August 31, 2019, 8:12 am

    Adopting a cartridge that will reduce the amount of ammo the average Grunt an hump by 2/3s is a damn stupid idea. Look at the cartridge comparison picture. If adopted this over priced/over engineered system will get a lot of our people killed after they run out of ammo.

    Only snipers fire at the ranges this cartridge is optimized for. Read a little history.

    • Roger August 31, 2019, 2:03 pm

      Agreed. …Also, I think it would serve US better if they would consider the chambering for the 6.8 SPC round instead, it’s still launches a 6.8 projectile, with greater terminal performance than the 5.56 NATO case while the casing is still comparative to the 5.56 NATO case. As well, leaving the barrel in a fixed position for optimal aim-point accuracy should be a must.

    • Roger August 31, 2019, 6:27 pm

      Agreed. …Also, I think it would serve US better if they would consider the chambering for the 6.8 SPC round instead, it still launches a 6.8 projectile, with greater terminal performance but the casing is still comparative to the 5.56 NATO case with minimal loss of magazine capacity and a negligible increase in recoil. As well, leaving the barrel in a fixed position for optimal aim-point accuracy should be a must.

  • Bad Penguin August 30, 2019, 4:36 pm

    I want to see this on a rifle with a 12 in barrel fired on full auto! The muzzle blast would be awsume!

    BTW Dont worry about our so called allies. There are no agreements as to the caliber of ammunition we all have to use. Our allies all switched to 5.56 because during the Cold War most of them had only one day worth of ammo even after they converted to 5.56. They knew we would resupply them if the balloon went up. They have even less ammo now.

  • Mike in a Truck August 30, 2019, 3:34 pm

    OK. So I’m an M60 baby. Humped one more miles that I’d like to forget. The only SA on earth that had to be safety wired togather to keep from shooting itself apart. This looks like a battle rifle to me- not a squad automatic. But I suppose its modular? If this is the real deal and they’re gonna release a civvie version then the market for AR’s just fell through the floor.It will be the next “must have.”

  • KMacK August 30, 2019, 1:56 pm

    Here we go again. The brass wants a new “Shiny” and this is it! Never mind that there are plenty of cartridges already existing that can match this new round’s performance and never mind that there are existing systems that are dependable and proven—the Generals want a new “Shiny” and thanks to the idiot in the White House, they got a huge treat in appropriations last year.
    We’ve been here before. When the military adopted Stoner’s pop-gun (which I carried in Vietnam), complete with bad design and reliability problems in both ammunition and the weapon itself, this sort of idiocy became readily apparent.
    Now we’re headed down the same road again, it seems. Why can’t those “shiny” loving idiots retire?

    • Tod August 30, 2019, 8:01 pm

      Ok, so don’t try and develop anything new just stick to the old tried and true shit that works huh??
      Where have I heard that ???

    • Alex Brooks August 31, 2019, 12:20 am

      So you are an anti Trump and anti Military officer idiot??? Putting down Generals who have served this nation for there adult lives. You are such an ass. You anti military puke.

    • Rane August 31, 2019, 5:47 am

      What cartridge already exist that mimics the performance of the new 6.8? I’m not saying you’re wrong I’m legitimately curious. The velocity for a 140 gr bullet from a 14” barrel is advertised at 3,200 fps from a case that looks about the same length as a .308 win. I can’t think of anything that mimics that in such a compact package in that caliber. The 270 weatherby mag needs a 3.2+” OAL and a 26” barrel to achieve these numbers. Even the 7mm ultra mag needs an OAL of over 3.5” and a 24” barrel to get close to these velocities with the same weight bullet(slightly larger diameter). The short barrel performance is key to the design of the next gen infantry rifle. The long guns are just too cumbersome for close quarters and their weight sucks on long rucks. I’ve been there.

    • FRANK C. MCLEAN, JR. September 17, 2019, 6:11 pm

      The idiot in the White House was Obama. Do you remember when ammo for civvies disappeared? – it was the Obama administration that planned and executed that fiasco. Where did all that ammo go, Iran I suspect? That idiot president sent Iran 150 BILLION DOLLARS in cash & for what? For a monetary backing of crazy Muslims against Americans in case of war. Obama was more than an idiot, he was a traitor against America and its citizens. If he would have pulled this same crap off in the 1950’s or 60’s, an ex-ranger or another ex-military sniper would have put a .308 Win down range in that idiot’s direction.

  • Evan August 30, 2019, 11:31 am

    Cobalt Kinetics makes absurdly expensive and utterly ridiculous AR pattern rifles that have “features” that nobody could reasonably want and lack features – like a forward assist – that are objectively good.

    I wouldn’t take anything that they do too seriously.

    • Big Al August 30, 2019, 2:12 pm

      I have always found the idea of a ‘forward assist’ tantamount to an admission of major issues with the AR pattern series of rifles.
      Why you find this a “desirable” trait is beyond comprehension.

    • Mark Roeder August 30, 2019, 6:01 pm

      Why do you think a forward assist is such a good thing? Do you really want to force your bolt into a situation that didn’t allow free run? Even if you allowed your weapon to get gummed up with carbon through lack of maintenance, a forward assist is not one of Stoners brightest ideas. This is especially true of a direct gas impingement system. It was thrown on to quell the belief of the troops this this was a ‘dirty” design. Without adding all that carbon to the action, you really should ever need a forward assist.

      • Gerard Depardeux September 1, 2019, 4:31 pm

        Sorry brother, I don’t have the source handy. I read some info on the Stoner, where the military wanted the forward assist feature added onto the rifle. Stoner was upset about the whole thing, he was adamant that it was not required. Be good to see some grunt feedback, how often did they have to use the forward assist out in the field?

    • Lance August 31, 2019, 11:01 pm

      I like to call it forward jam!

      • Michael Christensen September 8, 2019, 10:10 pm

        I have only used the forward assist in training while in the military. Never used one in the field.

  • RenfeMikado August 30, 2019, 11:12 am

    I noticed that the flash suppressor is not the bird cage style like I have seen on older AR pattern rifles. This style of suppressor looks like it could get caught on shrubbery and small branches when going through overgrown or wooded areas, because there is no “ring” at the tip of the suppressor.

  • Ti August 30, 2019, 11:08 am

    Getting there. I am a gun nut also. Anything that gets people looking at another angle in design is ok with me.

    Take all the weight that propellant takes, put in a quickly recharged “battery thingy?” , possibly an ammo “bearer”, and build an electromagnetic kinetic slug thrower. A supply of kinetic penetrators, thrown at high volume and any range out to the horizon if necessary would make a nice SAW.

  • Jay Loveless August 30, 2019, 11:07 am

    There’s no buagaboo about 60K pressure. SAAMI max for 7.62×51 is 60,191psi.

    • Rane August 30, 2019, 1:51 pm

      True, but in order to achieve these claimed velocities I would expect the pressure to be closer to if not over 70K

  • Peter Preston August 30, 2019, 9:28 am

    1. I’m not sure this is a true machine gun. A machine gun can deliver sustained fire for an extended period of time. The design does not look to be able to sustain automatic or constant burst fire for very long.
    2. The US cannot simply do away with the 5.56 unless it wants to abandon treaties and agreements with other nations.
    3. The average soldier does not need to reach out 1000 yards – the soldier needs to reach out 15 to 300 yards.

  • James Souvay August 30, 2019, 9:04 am


  • Kevin August 30, 2019, 8:13 am

    So you’ll next tell me that the optics are not connected to the barrel, those of us who own FN FALs will wonder how accurate that could possibly be.

  • Kevin August 30, 2019, 8:02 am

    I suspect it’ll really be fun to have your optics poke you in the eye each time the barrel cycles back….

  • Barry August 30, 2019, 8:01 am

    It will never work because due to the cartridge size the quantity of ammunition that could be carried by an individual troop would have to be sacrificed. Argue all you want about the effectiveness of the 5.56, but no one can argue that it is a powerful round and an individual troop can carry a much larger quantity of it than any other larger round. In the field you want quantity. I would vastly prefer carrying 1200 rounds of 5.56 than 500 rounds of 7.62, or whatever.

  • mark August 30, 2019, 7:34 am

    Interesting, but I suspect this is DOA. At least, the part where I read they want to shoot a 140 gr bullet at 3,200 fps from a 14″ barrel. That will be an insanely high pressure cartridge and that pressure will cause all sorts of problems. I’m sure the #1 criteria for a new SAW is to reliably keep putting out suppressive fire and the #2 criteria is to do this with as light an ammo as they can so the troops can carry as much as possible. I also believe that using the same cartridge as their carbines will be important to them. I don’t see this cartridge accomplishing any of those things very well. A lighter, more reliable 249 would be nice.

  • Jeffrey On crawford August 30, 2019, 7:29 am

    Shell is way too large to carry extra ammo and mags into the field. We always preferred to walk back out of the field,not run.

    • I Love Liberty August 30, 2019, 10:47 am

      They should have went with an intermediate rifle cartridge rather than this choice. This 6.8 millimeter General Purpose Cartridge looks like a replacement for 7.62 x 51 which is rather pointless since 7.62 x 51 is a great round out to beyond 600 yards. Is weight even less than 7.62 x 51?

      In my opinion they should have went with the 6.8 x 43 millimeter Special Purpose Cartridge or the 6.5 x 39 Grendel round over this.

  • Matt G. August 30, 2019, 7:25 am

    They might also want to think about re-engineering some hearing protection.

    • Rane August 30, 2019, 1:32 pm

      I’m not sure if you are being sarcastic, but I completely agree. The percussion of this round from a 14” barrel is going to be insane. They really should consider finding a compact light weight suppressor instead of the flash hider. Or at least a very effective liner compensator.

  • James Coles August 30, 2019, 7:21 am

    That sounds like a pretty cool, albeit complicated & expensive, rifle system…is it possible to make something like this system ‘soldier & field proof’?
    6.8mm rounds, such as the ill-fated M4 friendly but very useful 6.8×39 (.277 Wolverine) fill important niches but the long case 6.8/6.5 mm rounds I’ve seen generate so much chamber pressure that standard gun steel has a hard time keeping it all going the right direction.
    Yeah, this rifle, while kewl, looks to be wildly expensive & I fear not troop friendly.
    Which leads me to wonder if a rebarreling of existing AR platform rifles to.224 Valkyrie or 6.0mm Creedmoor could achieve DOD’s goals for accuracy & range at a small fraction of the cost…why not give these proven, relatively new calibers a deep look?
    Even upgrading to a piston driven upper for a .224 V rifle would be tons cheaper… and would take advantage of the most soldier-friendly rifle system yet devised.
    I think that within the DOD small arms community there is a ‘cool gizmo’ faction that wants cool & little or just kewl for the sake of kewl.
    I’m not sure this proposed system is the way to go in a period when there is lots of money flowing to DOD but the ‘good sense budget’ seems very constrained.

    • Ross August 30, 2019, 9:54 am

      The existing M4 rifles could easily be converted to .224 Valkyrie but to go to the 6 mm Creedmoor an AR10 platform. They could, however, convert to 6.8 SPC or 6.5 Grendel easily.

      • I Love Liberty August 30, 2019, 10:50 am

        .224 Valkyrie fires a round that is too small in caliber. The 6.8 x 43 or 6.5 x 39 Grendel would be a better replacement round for the standard infantry and you could use the existing M-4/M-16 receivers.

        This 6.8 millimeter General Purpose Cartridge is a disappointment to me thus far. And if you are firing this new round out of a 13 inch barrel you will feel like you are frying your face off. The muzzle blast is going to be very uncomfortable. They should stick with a sixteen or eighteen inch barrel for this rifle round.

      • Rane August 30, 2019, 1:22 pm

        As much as I love the 6.8 spc it doesn’t meet the criteria of what the next generation cartridge should be. The 6.8 spc solved only two problems that plagued the 5.56. That was power and SBR velocities. It’s a heck of a hunting round, but it won’t penetrate next gen body armor at extended ranges. The 6.8 caliber bullet is a great balance of diameter, BC, and terminal performance. Though the 224 V does great punching paper at long range thanks to high velocity and low drag, the 6.8 will do more damage. Not to mention the weight of the projectiles. The 6.8 bullets weight considerably more resulting in better on target performance. Most .223-.224 caliber cartridges require a longer barrel to achieve desired velocities. This is another issue that the next gen cartridge is trying to address. Most of us carry M4’s over here. That 14” barrel really dilutes the already questionable performance of the 5.56. The 6.8 caliber barrel benefits from short barrel performance thanks to it’s larger bore diameter and efficiency of the case and propellants. When I say 6.8 I’m simply referring to the bullet not any particular cartridge. If this gun can truly send a 140 gr 6.8 caliber bullet down range at 3,200 fps then it’s going to eclipse any other AR caliber 10 or 15. Plus it achieves that velocity from a 14” barrel. Their 18” version would be even more impressive.

  • triggerpull August 30, 2019, 7:14 am

    My 20 gauge browning semi-auto slug shotgun operates on a similar principal–and it is extremely accurate (I heard they may have gotten inspiration from that). The main problem I see here is the “fatty” design to accommodate an unconventional double-stack magazine arrangement. I don’t see a low-weight easy handle carbine out of this, and your ammo load weight has got to go up. Good news is–it will most likely be available on the civilian market no matter which way the trial goes for them. The market has sorely lacked an alternative to 2.26 and 2.8 COL for a very long time.

    • Bill Wright August 30, 2019, 10:54 am

      Remington Model 8…

  • Tony August 30, 2019, 7:01 am

    How can it be that accurate with the barrel moving and if it is after a while it’ll wear out then you will have accuracy issues

  • Dane R. Marley August 30, 2019, 7:01 am

    Where is the Bayonet Lug? I don’t think you can attach it to the barrel. They tried that with the Johnson Rifle and it didn’t workout too well.

  • Whyat August 30, 2019, 6:40 am

    Finally! , They re invented the “Johnson” it seems

  • Dave Johnson August 30, 2019, 5:26 am

    I’m a gun nut!!!

  • Nick M August 30, 2019, 5:15 am

    Pray that your flight won’t be on the Sabbath or winter.

  • James August 30, 2019, 4:19 am

    The 5.56x45MM NATO isn’t going anywhere any time soon. 5.56 & 9MM NATO are what the free world has standardized on. News Flash: 6.8 won’t replace 5.56. Ever.

    • Marine Grunt August 30, 2019, 7:32 am

      I agree, the 5.56x45mm will be with elements of our military for a long time as the AR-15 (M-4/M-16) platform has been refined to a ‘darn good’ and accurate combat rifle. However, in a war scenario, ammunition production and magazine availability is as important as the number of rifles on hand. We do, however, face a major problem! The Russian soldier’s body armor effectively prevents penetration of not only M855 rounds but even the highly touted M855A1 successor round. The Combat Arms branches (and in particular the Infantry Branch) of the US Army are desperate for a round which will reliably defeat this standard Russian body armor. The improved 6.8 mm round with a new rifle to handle appears the only practical answer. We can anticipate, that the Chinese will also quickly follow suit. A tough situation when only head or pelvic shots will stop a potential adversary! This is why, we are forced into the unenviable position of limiting this weapon and ammunition to selected units and logistically adding to the complexity of resupply.

    • Jay Loveless August 30, 2019, 11:03 am

      The fact that NATO has standardized on those two rounds is no longer any more significant than the fact that at one time 7.62x51MM was the standard. It certainly hasn’t disappeared, but it is no longer the standard infantry cartridge, either. Things can and do change.

  • Rane August 30, 2019, 3:47 am

    That is an insanely powerful cartridge! The .270 WSM can’t even hit those numbers with a 24” barrel. The chamber pressure has to be way over 60K to achieve these velocities. I would love to see what kind of propellant this cartridge uses. Something tells me it’s not traditional smokeless powder. That recoil system is very fascinating, but I’m leery about the longevity of the accuracy. What I mean is after the barrel locks back forward a few thousand times one would think it’s tight clearances would eventually become a bit looser. It will be interesting to see how this system holds up to abuse and high round count. Most barrels shooting that pressure and velocity have very short lives compared to traditional “.308” like numbers. That’s my other concern. But, I am glad to see progress. It’s long over due. We’re too easily out-gunned in our current load out. As I type this I’m currently deployed with an M4. The 5.56 isn’t a terrible cartridge, but in a 14” barrel it suffers from some serious velocity loss. The bad guys too often have hardware that out powers ours. This new cartridge seems to have rectified this issue beyond what I thought was conceivable. Which brings me to another concern, percussion. With so much pressure and such a short barrel this gun is likely to have some serious percussion. I would look into a compact suppressor to permanently attach to the muzzle. I am very interested in seeing how this project turns out.

    • I Love Liberty August 30, 2019, 10:56 am

      I agree. When I bought an AR-15 I went with the .300 AAC Blackout round for more power. The 5.56 x 45 is too underpowered for me. Using 124 grain bullets from a sixteen inch barrel the .300 Blackout is pretty effective to about 300 yards with the right shooter.

      I think the military should have went with an intermediate rifle round like the 6.8 x 43 or 6.5 x 39 Grendel over this new 6.8 General Purpose Cartridge.

      • Kivaari August 30, 2019, 5:18 pm

        The existing 6.5 and 6.8 loads that fit into an M4 platform cannot meet the demands of the army. The demands of the army are ridiculous, since achieving the armor penetration requires a magnum performance from a bigger rifle and machinegun. We will be using the M4A1 for another 25 years. The 5.56mm round is adequate for combat.
        This rifle and cartridge combination is too much – too much weight, too much recoil, too much muzzle blast, too much flash. The long stroke operation doesn’t lend itself to high levels of accuracy. Barrel life will be short with such a high intensity cartridge.

        • Rane August 31, 2019, 6:07 am

          Completely agree. I love my 6.8 spc, but it’s not a big enough improvement over the 5.56 to justify an extremely expensive military wide conversion. This new round however definitely addresses the power and penetration issues, but at what costs? My concern is like yours, the barrel won’t last with these pressures and velocities. That and I don’t think the recoil system is going to hold up for accuracy. I understand why they use this system considering the working pressures, but to claim it’s capable of 1,000 yard accuracy maybe a stretch. Especially after a few thousand rounds. Who knows, maybe they are using some new alloys(Adamantium) that only the government knows about that’s capable of holding up to these insane amounts of stress.

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