New HK121 Machine Gun

One of the lessons learn’t during the recent wars in the Middle East is that the 7.62x51mm owns the long distance engagement. The problem with 7.62mm weapons is that they are heavy. The new HK121 is a next-generation GPMG that is designed to be as light weight as possible.

The HK121 is still a prototype. The Visier magazine article (cover pictured above) states that it is a new design despite the external similarities it shares the the MG4. It weights just a few pounds more than the MG4 making it much lighter than the FN MAG / M240.

[Hat Tip: Max Popenker]

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.


  • Alaskan


    wonder if I had the money and wonder if the manufacture stamp reads Jan.1985.. 😉

  • Alaskan: Even if it predated the 1986 restrictions on US-manufactured machineguns, a foreign machinegun imported after 1968 would still be restricted under the Gun Control Act of 1968 That is why the majority of transferable full-auto HK are conversions of the semi-auto 90-series.

  • SpudGun

    Let’s hope HK have learned their lesson from the Mk 21 and that the barrel won’t melt after a couple of hundred rounds.

    After the GSG / ATI lawsuits, I hope FN takes HK to court over the design similarities of their SAW.

  • SoulTown

    I wonder much lighter this gun is compared to Mk 48 Mod 0-1, a comparison, I believe, is more fair one.

  • Marc

    “Let’s hope HK have learned their lesson from the Mk 21 and that the barrel won’t melt after a couple of hundred rounds.”

    Got a source or is this just another internet rumor?

  • lists the Mk 48 at 8.2 kg.

    Same site lists the MG 4 at 7.8 – 8.1 kg, depending on the version.

  • Brian

    From the FN website:
    Mk. 48 mod 1

    ”Technical Data
    Caliber: 7.62 mm NATO
    Barrel: 5.39 lbs.
    Overall Weight: 18.37 lbs.
    Barrel Length: 19.75 in.
    Rate of Fire: 730 ± 50 rds/min (Cylic)
    Range: 3600 m (Max.)
    800 m (Max. Effective)”

  • Big Daddy

    From what I read the MG4 is a POS and nowhere near as good as a SAW which is close to a POS. I read it is inherently inaccurate. One thing that I have read is that the M249 is very accurate and the shorter barrel was OKed because of it’s inherent accuracy, partly due to the weight.

    I never fired either, only M-60s.

    At least everybody is conceding that a machine gun shooting peas just doesn’t cut it. You need a big round to do what a machine gun was designed to do.

    Which goes to the idea IMO to completely eliminate the M249 from inventory and replace them with something like the Ultimax 100 which makes more sense as a SAW. Then introduce a light and heavy GPMG in 7.62mm NATO.

    Of course going with a 6.8mm or 6.5mm round would eliminate the need for a lot of those heavy GPMGs in 7.62 NATO and eliminate the need for a light one. Sorry to say that type of forward and logical thinking is too far advanced for any country’s DOD.

  • wsj

    @SpudGun: The barrels on the HK 21 never melted – cold hammer forged barrles made from the proprietary HK steel usually don’t do that 😉
    The problem was the lenght of the reciever, that’s why they developed the 21E version, and all was good.

  • Lance

    Good if the Military wants a light weight GPMG replace the heavy and bulky M-240 and ditch the underpowered M-249 with this new beauty.

  • Martin (M)

    Yes, Yes, YES!

  • SpudGun

    @Marc – As the Mk 21s were basically G3s converted to accept belt ammo, including firing from a closed bolt, it would heat up much faster then a purpose built MG. The designers realized the inherent flaws and made a big deal about the ‘quick change barrel’ feature.

    @wsj – Sorry, I forgot HK made it, so it cannot fail…ever. 🙂 (The fact that it failed numerous GPMG / SAW trials in lots of countries due to a litany of faults should be ignored)

  • Lance

    Persoanly id stay with a M-60 but a 7.62m GPMG is a worild better than a SAW or a 6.8mm MG. Id have firepower over light weight when a MG comes to mind!!!!!!

  • barry mackenzie

    MG3 is still available. the ‘improved’ new designs haven’t really bettered it.

    From the turks:

    The Greeks:

    Pakistan still make it as well I understand.

  • The HK121 is a different machine gun class then Mk 48, really general purpose MG, designed maily to the vehicles mounting points and RCWS, not the lightweight version for infantry. A true replacement of the MG3. Basic data: Weight 10,8 kg, overall length 1165 mm, barrel length 550 mm.

  • charles222

    ahh, yay, time to teach an Infantry 101 class again…

    The reason the SAW shoots 5.56 instead of 7.62 is this: WEIGHT. The automatic rifleman (the Army term for the guy carrying the SAW) is required to be able to keep up with riflemen carrying M4s. Now let’s say for a second that he had a Mk 48 or this and say, 400 rounds of ammunition for it, which is a pretty small amount for a fully automatic weapon. (It’s unlikely his teammates would be carrying extra ammunition for him, given that a fire team is not based around the automatic rifleman.) 100 rounds of 7.62 weighs…wait for it…wait..

    9 pounds. So now, with a relatively small amount of ammunition, the automatic rifleman is now carrying an eighteen-pound machine gun, and thirty-six pounds of ammunition. And that’s before his body armor, pack, etc. etc. And he’s going to be keeping up with soldiers who’re carrying (assuming a full basic load of 210 rounds for their M4s) about seven pounds of ammo, and maybe another eight of rifle? Yeah, sure. I can see that happening if your automatic rifleman happens to be Superman.

    Now, we have the SAW. Sure, it weighs sixteen or so pounds (less with the modernized Mk 46 variant) but it’s ammo is light. It’s approximately 3 pounds for every hundred rounds. This makes our 400 round load weigh just twelve pounds, and the usual six hundred round load weigh just eighteen pounds. Still darn heavy…but a good twenty pounds less than even a minimal load of 7.62 NATO when you factor in gun weights.

    Another thing: the M240 is heavy because the parts are robust as hell. The Mk48 doesn’t last nearly as long compared to it because it’s a third lighter; it’s why the 48 hasn’t been adopted for general issue and the six-pounds-heavier M240L has.

  • Marc

    “The designers realized the inherent flaws and made a big deal about the ‘quick change barrel’ feature.”

    Quick change barrels have been a great feature of machine guns for quite a while now, think MG42/MG3. I fail to see how this proves that HK21 barrels supposedly melt after low round counts.

  • SpudGun

    @Marc – I think you are taking me too literally when I said the barrels melted after a couple of hundred rounds. Compared to purpose built MGs, with parts designed for prolonged firing, including heavy barrels and open bolts, the HK 21s heated up far too quickly.

    Machine Gun barrels melt regardless of manufacturer, hence the need for quick change barrels. Unfortunately, the HK 21’s barrel had be changed more frequently then most due to the design flaws.

    So I apologize if you took my ‘couple of hundred rounds’ as literally ‘ exactly 200 rounds’. People would say that the Luger Pistol ‘jammed all the time’, I don’t think they literally meant that it would jam on every single shot, but compared to more reliable pistols, it seemed like it would jam all the time.

  • Christopher Garman

    wow that is a B-E-A-U-tiful piece of artillery…. would love to fire that a few hundred times…

  • Akmed

    There really isn’t any reason to get rid of the MG3, it’ s proven itself like the M2HB of the American Army. The Americans should rather dump the SAW in favor of the MG3, and get rid of the women in the army–which are the reason for all the concern about weight anyway.

  • Stahl

    Well it looks like a nice MG. but will it have the same pschycological effect as the MG3? That gun has proven it self for 68/9 years [Counting MG42, bascily same thing] But this new gun looks pretty intimidating.