Croatia’s Prototype Bullpup AK Conversion

The HS Produkt company, best known for making the XD pistols sold in the US by Springfield, was originally called IM Metal, and was a general fabrication company in Croatia. When the Croatian Homeland War began, there was a clear need for domestic small arms production, and the two engineers at IM Metal stepped up to try their hand at rifle design. The very first effort was a bullpup AK, intended to be made as a conversion of Yugoslav M70 rifles.

Only one example was made, and HS Produkt has kindly given me access to film it for you (thanks, guys!). The receiver was milled from steel billet, but mimics the construction of a stamped receiver, as would have been used in large-scale production (had that ever taken place). The charging handle has been removed form the bolt, and in its place a non-reciprocating handle mounted on the gas tube. The safety was moved forward to the trigger, but the selector lever left on the back of the receiver.

There are some neat ideas in this design, but it was clearly not up to the standard needed to serve as a standard Croatian Army rifle. The is how gun designers improve – they start with no experience and make some things that aren’t so good, and then learn and grow and improve. This is the first video in a periodic series showing the development of rifles by IM Metal / HS Produkt which ultimately lead to the VHS-2, so stay tuned!


  1. It is odd that I to watch in YT and comment in FW. Right in first sentence I am hit with faulty pronunciation, yet again. Ian, please check Croatian pronunciation beforehand – it is NOT KarlovaK, but KarlovaTS. It will give you some bonus points on top of your expertise. You do good strides in French already, try some Croatian now. Thanks for presentation.

  2. That’s how I always envisioned the ideal AK charging handle, based on the realization that the “gas tube” isn’t.

    The buttstock, OTOH? A pad on the back of the receiver makes for ideal LOP.

  3. Wait… what is exact definition of major European military power in 1990s and why does Austria (which is infinitely neutral since 1955) does count as one?

  4. One of the few “advantages” of an AK as the basis for a bullpup is that the receiver design easily lends itself to the addition of a decently-comfortable cheekpiece. Just rivet it to the stamped receiver cover.

    That said, once again we see that the self-loading bullpup is the answer to a question nobody with an ounce of sense would have asked.



    • One of the few “advantages” of an AK as the basis for a bullpup is that the receiver design easily lends itself to the addition of a decently-comfortable cheekpiece.

      I agree; a hinged (“Krinkov”), overmolded piece would be ideal. Other AK features advantageous for a bullpup are the hook-type trigger (works well in a front-pulls-back setup, which is inherently superior to a push-type) and ample room for a trigger rod.

      I certainly agree that a person “with an ounce of sense” would question why he would want a rifle with a poor trigger and/or ejection into his face shooting from the “wrong” shoulder.

      OTOH, once those serious concerns could be solved (and they have), he should start to question the 9-12″ of dead wood or plastic – intended to separate him from a long-gone external flashpan – between the buttplate / recoil pad and the other useful parts of the rifle.

      It remained useful as long as trigger and ejection problems persisted, but now that they’ve been solved one might question the conventional layout, when something 2/3 the size can perform the exact same functions without those (or any) offsetting drawbacks.

      • That 9″ of dead wood or plastic makes a huge difference in the ergonomics of a rifle.
        Bullpups inherently suck when it comes to handling.
        Pick up a standard M forgery and extract the magazine.
        Reinsert the magazine without looking at it, keeping situational awareness.
        Then try it with a bullpup.
        Then pretend you are trying to use your rifle as a club, which one handles better?
        These are life and death questions for the poor bloody Infantry of every nation.
        I can see some use for a Bullpup long range anti material/ anti personnel rifle, one with a 32″ to 36″ barrel.
        Or a long range sporting rifle, just for fun.

        • Bullpups inherently suck when it comes to handling.

          I guess it depends on the bullpup. My RDB is as handy as a big pistol, except better because the weight is balanced. It’s like carrying a toy.

          Reloading with the gun you’ve been training with (or similar) is obviously easier than otherwise, but that’s true either way. I find sliding the mag up into my firing hand more intuitive, just like a 1911.

          Then pretend you are trying to use your rifle as a club

          I’d prefer to use a rifle instead of a club, but nothing anywhere close to a bullpup’s compactness is going to make a good club anyway (or stay in one piece).

          I’m not saying bullpups are perfect for every situation, but they’re optimum for two situations: as a PDW that can actually replace pistols; or in CQB / home defense where the “support” hand is constantly needed for something other than support.

      • The bullpup fad began when several armies in Europe realized that they’d done two stupid things;

        1. They’d tried to turn their infantry fighting vehicles (IFVs) into light tank/tank destroyer vehicles while retaining the infantry function. Which meant less room inside for said infantry. (Let’s not get inrto the tactical blunders that result.)


        2. They’d neglected to consider that due to the economic and dietary improvements after the 1960s (when they stopped trying to be Socialist for a while), their better-nourished and etc. young men were now taller and bulkier. They kept designing their vehicles around average 5′ 7″ and 150 lb (1.7m and 68kg) soldiers instead of ones pushing 6′ and 190 lbs (1.8m and 86kg). With shoulders to match.

        To “solve” These problems? you guessed it; they did a third stupid thing.

        instead of doing the sensible thing and “raising the roof” (not to mention developing separate TDs to operate alongside the IFVs), they asked “How can we shoehorn the now ‘oversized’ infantry into our ‘perfectly designed universal vehicles’?”

        Answer? “Make their rifles smaller.”

        Problem: “We don’t want shorter barrels because we still want them to deliver accurate fire to 800 meters.”

        Answer; “Bullpup rifles!”

        The number of wrong-headed assumptions made are pretty obvious…now. (IFVs should not be playing light tank, they should be designed for the army you have now, rather than the one you had two generations back, and infantry riflemen should be engaging no further out than 250 meters; leave the longer-ranged problems to the support machine gun, vehicle-mounted weapons like auto cannon, artillery or CAS.)

        But the bullpup was the quick, easy, cheap and “kinda sexy” solution. (The Steyr AUG being an example; to me it’s always looked like a refugee from Star Trek. The L86? More a refugee from Doctor Who or Blake’s 7.)

        They took the “easy way out”. And like the U.S.Army with the M4 carbine, ended up with something that didn’t accomplish the mission and that nobody wants if they can get anything else.

        Darned intelligent people…combat infantry.

        REMF vehicle and Ordnance designers, and their “politically-savvy” superiors… not so much.



        • “Raising the Roof”:
          -Easier to detect, identify, and hit
          -Less fuel-efficient / shorter range
          -More wheel / track / tire / powertrain wear, spares, and maintenance
          -More top-heavy / rollover prone
          -More ground pressure / less off-road mobility
          -Reduced strategic mobility due to being compatible with fewer bridges, tunnels, railroads, ships, aircraft, and roads / trails
          -Requires more high-grade armor steel, machine time, and labor

          But hey, it lets us keep buttstocks!

          • Compare Warrior to Bradley. Then compare either one to M113.

            The further the IFV concept has strayed from M113, the less functional it has been as an actual “troop carrier”.

            As an ATGW-and-autocannon-armed tank destroyer, Warrior is a nearly ideal platform. As a troop carrier, it sucks.

            The more M2 Bradley “IFV” has become like M3 Devers “CFV” (i.e., tank destroyer/light tank) was originally planned to be, the less practical it has become as a troop-delivery vehicle.

            All of the above are bigger, heavier, and taller than M113, are slower and less maneuverable, have shorter unrefueled range, and have higher ground pressure. While having room for at most half as many soldiers.

            And yes, you can get in and out of an M113 with a reasonably-designed rifle. Like an M1 Garand, for instance.

            The answer is not to “enlarge” the present generation of “IFVs”. It is to design IFVs as IFVs, period, and not indulge in fantasies of playing Rommel with your “battle taxis”.



          • All my statements assumed comparable capability, and are valid in that context.

            If you build an “AFV” that is neither really armored, nor really capable of fighting, there might be some exceptions. Since we spent the next half century fighting musket-wielding peasants while building them roads and schools, it actually came out OK.

            In the conflict / mission set for which our AFVs were actually designed, the Soviets’ real AFVs would have enjoyed “playing Rommel” indeed – but I freely admit it would comfortably accommodate people armed with WW2 relics.

    • This looks like wooden copy of Crvena Zastava M70 family rifle grip.
      Only m76 sniper rifle had wooden pistol grips.

      For production economy, it would be much wiser to use the original, widely available plastic grip.

  5. Looking at this rifle and its dubious functions (magazine??) one gets a feel it was meant as a oneoff prototype from a getgo, for IM Met. to test the bullpup concept and their own skill in design amd production,
    and not a serious army contract effort – which is good, as pushing it further as such AKish thing, would only be wasted and disappointing.
    One sometimes should move from one design to the other different, instead trying to perfect a flawed idea – which they did perfectly successful with pistols; first PHP being semi-failure, second HS-95 ok, but nothing special, third HS-2000 instant hit and a legend.

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