Ultimax 100 Mk5 / General dynamics IAR

I have previously discussed the Ultimax 100 Mk4. This is the latest iteration of the Ultimax 100 design and is being entered into the IAR competition by General Dynamics, although it designed by Singapore Technologies Kinetics (STK).

Photos by SMGLee. Click to expand:

Quick Change Barrel

I like the design of the ambidextrous fire selector.

Compared to the Mk4 the Mk5 takes unmodified STANAG (M16) magazine, has quad rails and a bipod/foregrip rather than a separate bipod and foregrip.

I am not sure if the Ultimax 100 Mk4 100 round drum magazine will be made compatible with the Mk5. The Mk4 took modified STANAG magazines.

Ultimax 100 Mk 4

 Smglee Ausa Huge Dscn1084
Ultimax 100 Mk 5

UPDATE: Defense Review has more info.

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.


  • Now they need to make a belt feed version to sell the Army…

  • I have reservations about this bipod/fore grip combo. I can see its utility for an assault rifle, but a suppressive fire weapon like an ‘automatic rifle with bipod’ deserves a true bipod that offers more stability.

  • Daniel

    I doubt a belt-fed would be in the works as the Ultimax design was originally created for high-mobility firepower and MOUT scenarios, a belt-fed removes some of the mobility by being unable to reload on the move (not that I ever recall doing any reloading other than stationary) but most importantly, reduces the ability to fire almost straight up, an important consideration when trying to clear buildings with multiple stories as you’d have to provide covering fire up stairwells. The 249 was designed for stationary (base of fire) and open field support, so the design purposes of the 2 weapons are different, hence the difference in focus of what the weapon is good at.

  • Melvin

    Trust me…the bipod is more than able to work very steadily. This is due to the very low and controllable recoil of the weapon. You gotta fire it to understand.

    The standard bipod wouldn’t shift even on full-automatic fire.

  • happy

    The bipod/fore grip combo are great !!! It may be hard to believe, that is because like melvin have say it only when you fire it then you understand, because this is not another machine gun. The recoil is so low, that you could not believe you are firing a real gun.

    Thus it is the dream light machine gun, which enable you to run and shoot, very mobile and able to shoot in positions that you never dream of possible.

  • stopping pahwarh

    apparently it uses some “constant recoil” or “consistent recoil” concept or something that sounds like that… i dont quite understand it though

  • d3v

    “Constant recoil” here simply means that the heavy bolt group never hits the backstop in the receiver by using a longer receiver housing and carefully measuring the strength of the spring.

  • Devon

    I’ve done a lot of research and this is currently the best lmg out there right now…hands down. I wish our military’s weapon procurement would get over their political agendas and just pick the best weapons. This weapon is so much more mobile than other lmgs and is much quicker to reload because it is not belt fed. We should have grabbed this and not the 249 back in the eighties. I also think they should have dropped the m-16 and grabbed the daewoo k-2. Now we pay millions for weapons we don’t even end up adopting (XM8, OICW). This scar is costing us way too much and doesn’t even incorporate all the latest in weapon design (non-reciprocating charging handle, switch from closed to open bolt on full auto). How about some home-grown american designs? The RobArm XCR is excellent and the ACR looks very promising.

  • I shot this weapon a lot during my 2 years National Service in Singapore. It is a very easy weapon to handle, extremely accurate and low recoil. I can fire this weapon with hundreds of rounds with the Bi-pod up and the weapon will not even move an inch…its that good really.

    I am proud that our small country has an impact in the military circle…For eg, the Bronco, SAR-21, Bionix and so on…

  • chino

    First of all, the caption for the 3rd photo is is incorrect. The weapon pictured is the Mk 3,and NOT a Mk 4.

    While this picture is heavily used on the internet, it is in fact, a very early version of the Mk 3. It’s got a rare carrying handle that is different from most of the Mk 3 I’ve come across in SAF service.

    It’s got the shitty two-rod locks for the buttstock that, while common in the older Mk 3, were thankfully replaced in the later models with something that was much more sturdy.

    A “Mk 4” is the prototypes they sent to the USMC IAR trial, which looked more like the so-called “Mk 5” pictured here.

    There is also now a “Mk 8” revealed, as if anyone needs one.

    IMO, the Ultimax is still most useful as a SAW, and it is a true SAW in the vein of the Bren and other mag-fed rifle-calibre weapons.

    Reinventing it as a IAR for marketing purposes is just plain silly as it needs no such unnecessary cosmetic changes.

    The Grippod IMO is neither a good grip nor a good bipod, but a compromise. The worse thing about the Grippod replacing the bipod is its location, which is not forward enough, irregardless of the low recoil…

  • D’andre Bradley

    I think that the Mk5 should replace the saw because i feel it defeats the purpose of having a 240 gunner in a platoon. The Mk should be equipped with round drums, the 249 served as a great weapon from the 80’s til now but the belt fed that replaced it is the outstanding M240 series of weapons. The MK5 Iar would be a great replacement for the M249.