Shooting the World’s Lightest Machine Gun: The Ultimax 100 MK8 – SHOT Show 2020

The Ultimax 100 MK8 is the new brain baby of ST Engineering, and it is pretty awesome! ST Engineering is based out of Singapore, but they came down to SHOT 2020 to show us their new offering.

The Ultimax 100 MK8 proved to be extremely lightweight and was easy to shoot during our testing at Industry Day at the Range.

STE bills the Ultimax as the “world’s lightest machine gun that can be fired from a drum and reloaded on the move.” They may be right about that because the weapon is extraordinarily lightweight, coming in at only 11 pounds.

One would think that it would have some snap to it because it’s so svelte. However, STE’s “constant recoil system” makes it a real joy to shoot. In fact, they told us at Range Day that it’s recoil is so light that one could shoot it resting the stock on the bridge of one’s nose. True didn’t have the nerve to try that, tho, lol.

The Ultimax 100 MK8 fires from a non-reciprocating, open bolt and puts 5.56x45mm NATO downrange at a rate of 400-600 rounds per minute.

This LMG does not accept ordinary AR-style magazines. Instead, it uses M16-type and SAR21-type box magazines as well as 100 round C-MAG and Ultimax 100 drum magazines. When you buy an Ultimax 100 MK8, it comes with a cleaning kit, sling, 100-round drum magazine and foregrip with an integrated bipod.

The Ultimax takes an array of magazines, not the standard AR mag. That is because it is nothing like an AR: it’s the Ultimax 100 MK8 LMG.

Sadly, the Ultimax 100 MK8 is not imported yet, but they’re hoping to change that in the very near future.

Key Features:

  • Low weight of 5kg for the basic system
  • Constant recoil system with low felt recoil for accurate automatic fire
  • Modular design with quick-change barrel
  • Removable Lower Receiver with single shot and full automatic modes of fire
  • Open Bolt System with no cook-off constraint
  • Unique trigger safety mechanism that allows charging in safe mode
  • Retractable stock with height adjustments and can be removed for firing
  • Compatible with M16-type and SAR21-type box magazines, 100 rounds C-MAG and Ultimax 100 drum magazine
This LMG has a right folding stock.


  • 5.56x45mm NATO
  • 33.7″ long with a 35.7″ extended version
  • 11 pounds
  • 800 Meter effective range
  • 1:7 twist
  • 18″ barrel
  • 400-600 RPM
  • Safe, Semi, Auto
  • Gas operated, open bolt

See more products by visiting the ST Engineering website!

More Photos:

The charging handle is non-reciprocating.
The adjustable rear peep sight has yardage increments out to 1,000 meters.

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About the author: Riley Baxter is an avid and experienced hunter, shooter, outdoorsman, and he’s worked in the backcountry guiding for an outfitter. He also get’s a lot of enjoyment out of building or customizing his firearms and equipment. Check out Riley’s Instagram @Shooter300

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  • Bad Penguin February 5, 2020, 7:40 pm

    When they say M-16 mag they actually mean a steel mag.

  • JCitizen January 22, 2020, 11:22 pm

    UNIMPRESSED!! —- There are a lot of ARs out there the have removable barrels for cooling that are a LOT lighter than this thing. If I’m going to pay 3000 to $4000 dollars for something like this, it better be belt fed! These guys coming from overseas, probably don’t know the ARES Defense rifle is a LOT lighter and has a belt fed action. You can get almost any MG in semi auto, that is allowed in many states. That would be a much better investment. I hope to someday be able to afford a semi-auto M240 FN rifle, modeled after the US issued LMG. That is probably heavier, but then it is made for combat too!

  • Daddio7 January 22, 2020, 1:41 pm

    Who can or will buy this thing, law enforcement. Just what we need, amp-ted up ex military members spraying a crowd of protesters (gun rights marchers maybe).

  • Clint W. January 22, 2020, 10:40 am

    There was a day in the free USA when you would be able to buy this, with all the ammo you could carry, with nothing other required than putting down your cash. Up until the late 30’s. the Thompson sub-machine gun could be found in hardware stores for around 170 bucks, it was advertised, one ad calling it the ‘Ranchers Friend’ (could not find the ad, might have been the Farmers Friend), but it was depicted being used on a bunch of coyotes. With such a product available, wonder why nobody shot up schools and crowds back then? One reason, if you watch old newsreels or movies, the law said stop or I’ll shoot, the miscreant being armed or unarmed, running towards or away, those that did not do as told were dispatched on the spot. Usually with a few rounds from a .38, not a magazine full of 9MM from a Glock.

    • Ej harbet January 25, 2020, 2:48 pm

      And if the dirtbag survived we had this marvelous device called a electric chair which would after your trial and conviction be used to completely end any chance of recidivism and make society safe. We should bring consequences back.

  • Alan January 22, 2020, 9:46 am

    I sure wish they would have had the 100 round magazine full when he fired it. It would have only taken a few seconds more to fire the extra 70 rounds and prove it doesn’t malfunction.

    I have noticed in all videos from various weapon trials, they NEVER use the largest capacity magazine and fire until it is empty. Reliability in large capacity magazines is the most important feature for rifles, shotguns and handguns.

  • Drock January 22, 2020, 8:35 am

    Machine guns, designed for sustained rapid fire produce a lot of heat. The open bolt at rest design allows for more cooling air to flow and doesn’t leave a live round in the chamber. A closed bolt over a live round in very hot gun can cause the round to “cook off”, or fire due to the heat.

    Disadvantage is when the trigger is pulled, there is quite a lot of metal moving before the gun fires. This makes the first shot not as accurate. Moot point in an area suppression weapon like a machine gun.
    Another disadvantage to not having a round chambered is chambering the first round from an open bolt is not a sure thing. That is why open bolt guns are often not used as entry weapons.

  • Slim January 22, 2020, 5:19 am

    Can someone please explain to me the difference between an open bolt and closed bolt setups? Advantages and disadvantages on both sides would be great. I usually hear about older guns firing from an open bolt which to be honest I don’t fully understand what that means. Also I’ve noticed bigger or should say huge rounds that our military uses on their ships. I’d sure appreciate the info!

    • Alan1018 January 22, 2020, 8:12 am

      An open bolt has a sear that holds the bolt in the rearward position. When you pull the trigger the bolt moves forward, strips a round from the magazine (or belt) and the round fires as the bolt closes.The gun is cocked and ready to fire when the bolt is open (at the rear). Thompson, STEN, MP38/40, grease gun. Closed bolt is your AR, 10/22 etc. The gun is cocked when the bolt is closed.

      • Walleye January 22, 2020, 10:25 am

        Three other rather infamous open bolt guns are:
        1. The BAR (Browning Automatic Rifle). Even though it is mechanically an open bolt design with a big heavy bolt moving forward striping a round out of the magazine prior to firing the cartridge, I have found it to be exceptionally accurate.
        2. MAC 10 & M-11 family of sub-machine guns. They consist of very few and mostly stamped metal parts, light weight, yet very reliable and controllable for what they are designed for.
        3. UZI Sub-machine Gun. It is ubiquitous and legendary history speaks for itself.

    • Terry L Davis January 22, 2020, 8:22 am

      In an open bolt, the firing pin is permanently fixed to the bolt. Ther is no hammer or a striker as per se. The bolt is held to the rear and activating the trigger releases the bolt which then strips a round out of the magazine and fires the round as soon as it is in battery.

      • JCitizen January 22, 2020, 11:35 pm

        Just for information purposes – the US 1919 LMG fires from a closed bolt, you can fire the same design in the M2 HBMG .50 cal with the bolt held to the rear ( in case the barrel is hot) and it will not fire when the bolt closes unless you hold the butterfly trigger down as you release the bolt. The US M60 LMG ( for example) fires from an open bolt, but the firing pin does not hit the primer until the bolt is closed and the trigger is pressed or held down

        The BATF will not approve a semi-auto with an open bolt design, because they claim that is the 1st step in making it a machine gun. that is why all the UZIs and MAC pistols fire from a closed bolt. The early MAC semi-autos had lousy hammers in them, because it was primarily supposed to be a solid open bolt design, just like the ones you mention.

        • Ej harbet January 25, 2020, 3:11 pm

          I testify to the lousy hammers!
          In the late 80s i had a m11/9 that after breaking the hammer fired 6times before stopping. Glad it didnt break on shot 1 and that i had a good grip on it. Swd sent me a new hammer but i never quite trusted it again

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