Swiss K31 lives on through the TW-73!

Most small arms development is seen as being forward thinking, with new designs leaving the older ones in the dust. But for some, the complete opposite is the case (such as the FNC and SCAR). In this example modern day riot police in Switzerland are using chopped K31 straight pull rifles converted to fire tear gas grenades or rubber bullets against uncooperative protesters. The designation is Trnengas Werfer 73 (Tear Gas Thrower), or TW-73 for short among the police that utilize it. It is also designated as the Mehrzweckwerfer (General Purpose Thrower) MZW 73/91.


Due to the designation in 1973 from the name, it appears that the modification was introduced on the tail end of the K31s service in Switzerland, and stocks of the variant were simply kept over and used to supply the police forces, with which they are extensively used today. This appears to be a case of “If it ain’t broken, don’t fix/replace it”. Due to the seemingly built up chamber, the use of blank rounds, and few occurrences of actual operational use per year, I would assume these launchers don’t get pushed to their maximum operational capacity. That being said, they should be usable for many years to come.

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The police in this photo are wearing a sort of loading vest, so a buddy can withdraw a round from an officers back, and either hand it to him, or load the launcher for him.19003075

Below are some videos of Swiss police in action with the TW-73. The riot police look well versed and trained in the system, firing coordinated volley’s and loading each other’s launchers. You can also see the vast amounts of rubber bullets on the street.


Infantry Marine, based in the Midwest. Specifically interested in small arms history, development, and usage within the MENA region and Central Asia. To that end, I run Silah Report, a website dedicated to analyzing small arms history and news out of MENA and Central Asia.

Please feel free to get in touch with me about something I can add to a post, an error I’ve made, or if you just want to talk guns. I can be reached at


  • Tassiebush

    That’s a very useful conversion. Great linked bits of footage too. You could see them working the action and front loading the cup/barrel. Just the thing for cranky people with silly hair!

    • Dougscamo

      I especially liked the tactical resupply wagons….

      • Tassiebush

        I really liked the screens added to landcruisers.

  • DW

    Import this to america and see if this can lob soda cans more accurately than the X-product’s offering

  • ladd

    Unfortunately beer cans do not work as ammunition, the enemy just catches it midair like a drunken matrix Neo and drinks it in 2 seconds, like the revenge of the nerds guy but latino, making them even more powerful.

  • gb

    I loved working with that. It has quite a hefty kick to it. on the ring of the Tube you can ajust how far the Gas canister will fly. maximum distanz was somewhere aroun 160 meters when fired in extrem Arc. The timer fuse of the canister is set to 2.5 Seconods. but you can unscrew them and the they fire right after exiting the tube. Its like a dtear gas spitting dragon then.

  • cwp

    Very useful, I’m sure, but it makes me wince seeing those wonderful rifles torn up so they can be used for riot control.

    • iksnilol

      better than rusting away from not being used.

      • Paladin

        They could give them to me instead, I’d make sure they get used.

  • OCG

    I can see why the Swiss would use these, they have enough spare K31’s lying around they sometimes trip over them.

  • DIR911911 .

    “the complete opposite is the case (such as the FNC and SCAR)” . . . what?? elaborate please , tell me how a gun (scar) everyone seems to want one of is being left behind by older rifles.

    • DGR

      While most people think that “everyone” wants a SCAR, sales show a very different story. Militaries want AR rifles not SCARs. Seems every month there is another military that is adopting the AR platform in one variant or another, nobody is buying the SCAR or FNC in any kind of similar numbers.

      • anon

        There are a lot of factors that go into procurement. ARs are cheap, and have a long history. It’s not surprising they are being adopted heavily. The one that does surprise me is the HK 416/417. Between the SCAR, and 416/417 I’ll take the SCAR all day. Yes, I’ve shot both.

      • cwp

        Everyone wants a SCAR. Then they get a look at the price tag.

  • Aaron Willhoite
    That K31 would make a Jawa proud. Maybe this is where they got the inspiration?

  • Swarf

    I’m really going to try and incorporate “werfer” into conversation today.

  • yukon cornelius

    Do the swiss even have riots? When a riot begins, do they just call up their reservists, and the riot ends since they all have to report for duty? Just a thought…

    • Swarf

      Grrr! We’re so mad! Let’s have a riot!

      Hey, there’s a riot, everybody report for riot duty!

      Well, looks like the riot’s over, everybody is released.

      Hey, We’re off duty, let’s riot!

      I think you’ve discovered a Swissfinite Loop, Cornelius.

      • yukon cornelius

        “Werfer tiny pocket knives” hahaha! With assault-style hi-capacity tweezers!

      • Dougscamo

        Didn’t I see a version of this in “Dr Strange”?….

  • TheNotoriousIUD

    Is that cop shooting the other cops in the back?

    • Arie Heath

      Seems to be a training exercise. Most likely similar to when police officers get pepper sprayed by other officers during training.

    • Dougscamo

      When I became a munitions instructor, the students had to endure being shot with all of the less-than-lethal munitions…..rubber buckshot….rubber shot-dispensing grenades….some legal mumbo jumbo to avoid the dreaded excessive force claim….

  • nova3930

    Hate to see a fine rifle butchered like that.

    • Dario B.

      the problem is that we have so many of them that it’s not that regrettable

      • abecido

        I regret them not being sold on the US market, despite already having two.

        • Dario B.

          it’s not easy to export weapons from switzerland now…

      • nova3930

        If you just want to dispose of them then ship them over to the US. They’re getting hard to find here.

        • Dario B.

          today it’s not easy to export them, but.. i prefer to see them in a swiss basement than in the hands of many edgy gun enthusiasts just because they are “cheap” historical guns…

          • Dougscamo

            They aren’t cheap in the US anymore…..a good condition K31 is going for around $650….unless you consider that price cheap….

          • Swarf

            Speaking as an edgy American gun enthusiast, I’d rather see that, too, Dario. Keep them at home, in homes.

            But, I’d rather see them in my edgy hands, than chopped up to gas hippies.

          • Doom

            what’s wrong with gassing hippies? especially pro “refugee” hippies? Id say the gas being used is a bit weak actually.

          • JohnHR

            Might be “cheap” in your neck of the woods but as an imported mil-sup rifle to the U.S., not so much. I avoided but one one for a long time because the price of ammo was more than I cared to spend. Ammo prices decreased, somewhat and I went ahead and brought one.
            Mounted a Leupold VX-3, 6-18×40 on it with a side mounted scope mount and went to the range. At 100 yards it made very nice clover leaf’s. At 200 yards the average group was 2 to 3 inches and I had no problem hitting a 18×18 inch steel plate.
            I take it your assumption is that collectors buy mil-sup firearms and bury them in a safe never to see the light of day again. If so, you are misinformed. I, and others like me, shoot, maintain and care for our mil-sup rifles because that’s what we fo.

  • iksnilol

    I sorta want to replace the rubber balls with steel ball bearings and see the effects on gel.

    • ostiariusalpha

      Oh, is gel the name of your neighbor’s cat?

      • iksnilol

        More correctly, 3 half feral cats that stalk around my house.

        Fluffy bastards is all I will say.

  • abecido

    I don’t know if I’d call this “living on”. It’s like some grand old warship being converted into a prison hulk or oil jetty. At best, it’s a kind of undeath.

  • Frank Stratton

    Just another cost saving measure. US used 45-70 trapdoor Springfield rifles in WWII converted to line throwing guns.

  • Matt Atchinson

    What the Hell Switzerland, butchering some of the finest rifles ever made…….Why? My understanding is a lot of Swiss citizens still use these for target shooting competitions, Why not sell the rifles to them? My Swiss friend says that competitive shooting is still very popular in Switzerland. Or sell on the surplus market? These aren’t like a Mosin or a K98, A little over 500,000 were made. Not a huge number by any stretch.