BREAKING: Heckler & Koch HK237 and HK337 in .300 Blackout / Whisper, RUAG producing ammunition

BREAKING NEWS from Nürnberg, Germany: H&K is manufacturing rifles chambered in .300 Blackout / Whisper. The doors to the Enforce Tac expo literally just opened minutes ago (at time of writing) and as we walked in we were surprised to see the new HK237 and HK337 chambered in .300 AAC Blackout / .300 Whisper. The new HK carbines are displayed together with new .300 BLK ammunition manufactured by RUAG.

.300 Whisper is a CIP standard cartridge, developed in the early 1990s by J.D. Jones of SSK Industries and .300 AAC Blackout (.300 BLK) is a SAAMI standard cartridge developed by Remington based on the .300 Whisper.

RUAG’d new .300 Whisper load was developed in co-operation with B&T (CH) and it tests well out to 300 meters. They wrote …

At an operative range of approx 150m, special police and military units use the powerful .300 Whisper primarily in urban areas against secondary targets such as alarm systems, fighting dogs or cameras.The deformation ammunition .300 Whisper SWISS PHV Styx Action (HV=High Velocity) widens the application spectrum and provides highly precise hits also at 300m. The range of ammunition enables the shooter to move from subsonic to supersonic by a magazine change within seconds in order to remain efficient and convertible.

The lighting condition at this exhibition made is almost impossible to take good photos, so please excuse the quality….

Photo by Jan-P. Weisswange

Unfortunately there is not much more information available at this time. H&K are good at the strategy of displaying first and releasing the information at a later stage, which is frustrating for fact-seekers.

My conclusion: The new HK carbines look like HK416 and G36, but re-barreled to accommodate new calibers. If there’s more to it I’m sure we’ll find out soon.


The below pictures are courtesy of Frag Out Magazine and Soldier Systems.

HK237 (G36 variant). There’s so much I want to write about the ergonomics of this stock… What is going on there?

HK237 Close-up …

Helmet stock.

Fully automatic.

The HK337 – looks like a HK416 but the caliber is on steroids, .300 Blackout or .300 Whisper….

HK337 Close-up…note the serial.

Very compact, fully automatic.

Bonus picture below: HK433. Still in 5,56×45 mm, but there are rumors about a .300 Blackout / Whisper version as well.



Eric B

Ex-Arctic Ranger. Competitive practical shooter and hunter with an European focus. Always ready to increase my collection of modern semi-automatic firearms, optics and sound suppressors. Owning the night would be nice too.


  • Anonymoose
    • KestrelBike

      hahahaha. these kill me.

      I really want to know more about that HK333, though. If it’s their budget rifle, or if they’re specifically trying to compete against (MSBS? Who was/is going to adopt that beside the manufacturer’s own country?)

  • Guy Slack

    Huh. Pretty cool.

  • Joe

    Goofy stock is for ballistic helmet visor.

    • Osramicus

      Looks like it keep ambi controls and ejection port clear when folded, too.

  • some other joe

    Is that a ZO 4 mounted on the 433?

    • chris

      it probaly is since the german army is using the ZO 4×30 for the last about 5+ years to replace the older straw like scopes and they wnat to marked the gun to the german army

  • Rob


  • Rob

    Also of interest is that this is the first time we are seeing the hk433 with the paddle mag release lower publicly.

  • JumpIf NotZero

    Interesting because 300 Whisper isn’t recognized to be any standard, and .300 BLK isn’t even the real name for 7.62×35

    • Jared Vynn

      1st there is a CIP standard for 300 whisper which is required for sale of the cartridge in Europe, second 300 blk is SAAMI short hand for 300 AAC blackout. 7.62×35 is merely another name for the cartridge but isn’t the most commonly used name.

    • Audie Bakerson

      The Dutch have already adopted the round

      I imagine their contract will give us a true “standard” for the round.

      • Johnsmyname

        Oh man, imagine surplus .300 blk from EU! 🙂

        • Tonewall Jaxon


  • NukeItFromOrbit

    I fail to see any appeal in .300 Blackout. If I wanted 7.62x39mm ballistics I’d go with that or go with the somewhat better 6.8x43mm.

    • Bean Guy


      • Jared Vynn

        And a much wider range of projectile weights and easier conversion of existing platforms.

    • CommonSense23

      Its for shooting people without waking up the neighborhood, while still having rifle ballistics in the mag.

    • gunsandrockets

      I’d say the appeal boils down to commonality, and the lower costs which flow from that commonality: common sized .308 bullets, common sized 5.56mm magazines, common sized 5.56mm bolts.

    • snmp

      for the G36 in .300 Whisper you could found the SL9 SD (Silencer)

  • J.T.

    I guess they finally got tired of seeing all their European law enforcement customers buying the SIG MCX instead of their guns.

  • Michael R. Zupcak

    Any idea why the ballistic visor is so popular in the EU but seems less popular in the US? Only drawbacks I can think of are cost and discomfort.

    • F

      It shields from pistol rounds, not Rifle rounds.

      • micmac80

        yes in in hybrid config a 44mag at point blank but troughout the coverage with no weak points.

  • John

    I have to ask: What’s it matter?

    HK won’t be selling these in the U.S.

    • snmp

      the Tow Car are Landrover Defender (from TATA Motors)

      • Garavella Yk

        the Defenders were discontinued in 2016 (rumor has it the TATA made ones were not the same quality)

  • No one

    .300 Blackout, still a mistake.

    • Tinkerer

      Said No one.

      • No one

        Well you’d technically be right I guess.

        • Tinkerer

          The Best kind of right.

    • Dana King

      You’re an id10t.

  • malachi13

    So if HV is High Velocity? What’s PHV mean? Pretty High Velocity?