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Explained: The U.S. Army’s Next Generation Squad Weapon

M4 Carbine Ready
Lance Cpl. Brian Schaeffer, a rifleman with 1st Battalion, 9th Marine Regiment, scans for threats during a firefight with insurgents near the Bari Gul bazaar in the Nad Ali district, Helmand province, Afghanistan, Dec. 4, 2013. Nearly 100 Marines and coalition forces service members engaged in the firefight with insurgents while patrolling the area to interdict Taliban movements and gather intelligence around the bazaar.

The U.S. Army’s ambitious Next Generation Squad Weapon, intended to be a catch-all replacement for the iconic M16, M4 carbine, and M249 Squad Automatic Weapon. There are currently three firms in the running, and have offered fairly different platforms — and testing is now in its final phase.

All three of the contenders are built around the 6.8mm Special Purpose Cartridge, a government-designed medium-caliber rifle cartridge that falls in-between the 7.62mm and 5.56mm NATO cartridges in terms of bullet diameter. Though the actual bullet is mandated, what the cartridge looks like is up to the individual NGSW entrants. One thing that all three firms’ entrants have in common, however, is a removable suppressor.

Next Generation Squad Weapon: Who Is In the Running?

The Defense firm General Dynamics’ offering is perhaps the most radical of the three. Their bullpup design sees magazines loaded behind the trigger group, offering a longer barrel length — and therefore higher muzzle velocities and increased maximum effective range — while maintaining a very compact overall length.

General Dynamics partnered with True Velocity to develop what they think could be the next revolution in ammunition. A Texas-based polymer ammunition manufacturer, TV’s ammunition is radical — by exchanging brass ammunition casings for plastic, TV claims that significant weight savings can be gleaned, and therefore allow grunts to hump more ammunition around.

Sig Sauer’s entry is perhaps one of the more conventional of the three competing designs. A conventional, non-bullpup layout is completed by hybrid ammunition. By using a steel base and polymer cartridge body, Sig Sauer claims that sufficient weight reduction can be made with sufficient case strength to handle the 6.8 SPC’s increased chamber pressure.

On the other hand, Textron’s ammunition is the most bizzare-looking — they decided to design their platform around telescopic ammunition, wherein the entire bullet and propellant are encased within the cartridge case, offering a more compact, lighter cartridge. Though on paper there are significant gains to be made with such ammunition, the technology is extremely green and untested.

Changing Times

It’s not just the U.S. Army that is going through a small-arms evolution. The U.S. Marine Corps has also fairly recently forgone their M16 rifles and M4 carbines in favor of the M27 rifle, which is still being rolled out. However, new isn’t always better.

The supposed weight savings touted by the Army by using plastic casing rather than brass may not be as great as they seem. Individual soldiers don’t always carry enough ammunition to take full benefit of a reduction in ammunition weight — the greatest benefit would be logistically, to the ships, planes, and trucks that move large quantities of ammunition, not to the individual soldier.

Furthermore, using plastic cases could come at an inopportune time. Dr. Allan Orr, a Sydney-based anti-terrorism specialist explained just why the Army’s new ammunition might not be the best idea, explaining that “the Great Pacific garbage patch over the next 50 years will only increase at a time when the world is trying to get on top of it.” This has also led to some speculation that light-weight plastic ammunition could be a hard sell for European NATO Allies, due to potential difficulties in getting more environmentally-friendly countries onboard with plastic NATO-standard ammunition.


All three contenders have two versions of their weapon systems in the running: 15 rifles and 15 automatic rifles plus 180,000 rounds of their own cartridges. The various platforms are currently being tested and evaluated by U.S. Army soldiers. There should soon be a winner. 

Caleb Larson is a Defense Writer with The National Interest. He holds a Master of Public Policy and covers U.S. and Russian security, European defense issues, and German politics and culture.

Written By

Caleb Larson, a defense journalist based in Europe and holds a Master of Public Policy degree from the Willy Brandt School of Public Policy. He lives in Berlin and writes on U.S. and Russian foreign and defense policy, German politics and culture.



  1. Steven

    November 25, 2020 at 4:26 pm

    I am interested if the proposed squad automatic weapon is gas piston operated, similar to the AK system or has an operating system similar to the M16, which is more prone to fouling.
    Certainly lighter weight ammunition would be good for people carrying it, which is already a major deterrent.
    Apparently it’s not a replacement for the M60 machine gun, using 7.62 ammunition.
    It would be good if there was commonality in ammunition between the machine gun and squad and individual soldier’s weapon, with less of a problem with logistics, manufacturing, contracting, the entire logistics system.
    Will the new weapon system be a fantastic advance, similar to introduction of breech loading over muzzle loading, or mini-ball over round shot?
    Will everyone have controllable full auto option?
    Will everyone in the squad be involved in carrying ammunition?
    As technology advances, targeting and night vision improved, even autonomous weapons which will fire more accurately at a designated target than any but the most experienced rifleman, it seems massed firepower has become more important, essentially the deterrent effect of lots of ammunition impact downrange.
    What may be the deciding factor in the future is cost and appropriations.

    • Fungus Gnat

      November 26, 2020 at 7:54 am

      The M-16 is gas operated.

    • Ryan W

      November 26, 2020 at 5:06 pm

      1. The m16 and all AR platform rifles are gas operated, and the fouling issue was solved during Vietnam because our government used a cheaper and corrosive gunpowder that they were told not to use by Eugeno Stoner and Colt. Once they corrected the problem the rifle was very reliable.
      2. The M60 has basically been retired since the 90’s. Only special ops teams are reportedly still using a version of the M60 today and only in some situations. The 7.62 caliber machine gun the army and marines rely on today is the M240 Bravo. The 240 outclasses the M60 in all the important categories and is lighter to carry.

      • D Y

        November 26, 2020 at 7:52 pm

        About the only negative to the AR design I’d argue is the amount of heat transferred to the bolt. For most of us, that would NEVER be an issue. But in a prolonged firefight, it can be. Add to that the volume of fire that the SAW or 240 is capable of, and piston operation (of some sort) makes sense in the machine gun role. Thus one of many reasons the SAW and 240 use pistons of one form or another.

        Its definitely not fouling, as mentioned that is not an issue. You can talk with people that have fired 1000+ rounds through an AR design (I’m one) without anything but barrel cleaning and periodic lubrication if the bolt carrier, and zero malfunctions.

  2. Snake ANGLICO USMC Ret

    November 25, 2020 at 6:10 pm

    In some firefight, we snapped the belts of the M-60 machine gun ammo for our M-14’s when we were running low. Remember, the rounds should have the same cal and the idiots in the rear who have never been in a fire fight do not seem to realize this. Also, plastic casings will jam when engaged in a very prolong and hot fire fire because it will MELT.

    • Fungus Gnat

      November 26, 2020 at 7:52 am

      May not melt but as you correctly point out, heat and plastic don’t go well together.

    • Daniel

      November 26, 2020 at 5:48 pm

      They use the term “plastic” but it is more complex than that, and it has been tested in prolonged shooting without adverse affects. The tech has been around for some time

      • D Y

        November 26, 2020 at 7:56 pm

        The Abrams 120mm “casings” are “plastic” as well. As mentioned, more complex than that, it’s part of the propellant charge apparently. Or at least is consumed on firing.

  3. frank barquist

    November 25, 2020 at 11:13 pm

    Sigs ammunition while it being hybrid is actually a steel base and conventional brass casing not polymer. The hybrid combination allows case pressure to achieve a Maximum of 80,000 psi where as all currently available ammunition has a maximum of 65,000psi. Everything else was correct, if u would like to fact check Sammi just approved the civilian version of sigs new ammunition as the Sig 277 fury.

  4. Fungus Gnat

    November 26, 2020 at 7:51 am

    ” weight savings can be gleaned, and therefore allow grunts to hump more ammunition around.” – but a lighter bullet means less impact and penetration.

    It is interesting that the diameter of the bullet is very close to 7mm, which was the Japanese standard in WWII

    • Ryan W

      November 26, 2020 at 4:46 pm

      You don’t know much about ballistics do you? Just because a bullet has a nearly identical diamater doesn’t mean theyre the same size and weight. A 7mm round can weigh twice as much as a 6.8mm round depending on the type of bullet used. Japan used a 6.5x50mm and 7.7x58mm round for their Arisaka rifles in WWII. The 6.8spc is a 6.8x48mm round usually weighing 115 grains or so and hit with 1700 ft/lb of energy. The Japanese 6.5 used a 139 grain bullet and had nearly 1,000 more ft/lb hitting power. Even though it was smaller than the 7.7×58 round it was superior in velocity and energy than the bigger round.

  5. D Y

    November 26, 2020 at 7:46 pm

    This is already doomed to be a disaster.

    Mandating a specific cartridge results in the complete elimination of revolutionary improvement and advancement. See the M1 Garand or M14 for examples of where government mandates stifled improvement. Not that they aren’t fine rifles and an advance…but the cartridges and features of said weapons were dictated, when the weapons could have been even better. I’d throw the M17/19 pistols in there too, but I guess we don’t want to argue about how the US has the only military on the planet who can’t train troops to keep their fingers off the trigger of a Glock. But those would be the same people pushing the 6.8, and the same people that conspired to keep the US Military using metal magazines when they knew full well the polymer variants worked better.

    If SIG can push their hybrid cartridge to 80,000PSI, using a non-scientific comparison, it could be possible to reduce the size of a cartridge 25% while keeping current performance levels. That alone would be massive, AND leave room for growth. But no, we REQUIRE a bigger diameter bullet (with worse ballistics than a smaller projectile), which necessitates a larger firearm, and bulkier/heavier loads for troops.

    Let’s force industry to use a round that was designed 18 years ago (with Remington no less, where are they now? Lol), and does nothing to take advantage of modern projectile designs. 6.8 is akin to round nose 30-03 loads. 6 or 6.5mm rounds make far more sense today than 6.8. There are about HALF as many .277 (6.8spc bullet diameter) bullets on the market compared to 6 or 6.5MM bullets

    An unaerodynamic bullet does NOTHING to ensure commonality between rifles and the SAW, while being effective against soft targets at further distances. Just by looking at the SPC you can see that it is severely lacking in the technology that has given rise to rounds such as the 6.5 Grendel and 6MM ARC. Now imagine if the gloves came off and the government just told industry the expectations, and let industry cone up with a solution? Instead, we are theoretically going to be stuck with a round that was designed upon the magazine and rifle limitations of the M16,tracing its roots back to the 1950s.

    How are we going to move forward with thinking like this?

  6. Mark A Laughlin

    November 26, 2020 at 9:34 pm

    All NGSW candidates are poor options.

    All Gunfighters need ambidextrous instruction to make optimal use of cover. Once gunfighters are truly, fully ambi, testing will prove that perfectly mirrored, ambi, bullpup rifles are essential for the Ambidextral Gunfighter. Videos and free booklet at…

  7. John

    November 27, 2020 at 9:35 am

    This is horribly written

  8. James Drouin

    November 27, 2020 at 11:08 am

    The entire concept of “grunts needing a larger round” is some General’s wet dream.

    The military (in general) has different weapons for different purposes, and if the M4 isn’t effective beyond 300m, then the 7.62 certainly will fill the gap … until the .50 is needed, or mortars, or a Bushmaster, or a 105, or, or, or.

    Colossal waste of taxpayer money.

    • D Y

      November 27, 2020 at 11:38 am

      Well, no. 7.62 and 5.56 are both dated. Modern rounds can more effectively fill most if not all of those roles.

      Less weight, lower recoil, better ballistics. Why stick with the old stuff? There is a reason other rounds have been tried in the recent conflicts.

      I do agree the larger bullet idea being stupid. Definitely so with modern plate body armor. More velocity will defeat it, not larger diameter, if speaking similar weight projectiles.

  9. david

    November 27, 2020 at 10:00 pm

    The M4 has hit its stride and I dont think any of those should fully replace it. Maybe we need a heavier AR for armor pen but the M4 should stay as the ‘carbine’ of our times.

    Maybe someday the M4 will be like the M1 carbine was in the WW2 era.


    February 19, 2021 at 8:55 am

    Yes! Finally something about Rifles.

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