S&T Dynamics XK13 OCSW Project Cancelled

The Korean Joint Chiefs of Staff have announced the cancellation of the S&T Dynamics XK13 that has been in development for a number of years. The OCSW-style (Objective Crew Served Weapon) automatic weapon fires 25mm grenades. The military had expected it to be able to replace both their K4 automatic grenade launchers and M2 Browning .50 cal. machine guns. Three rounds were in development for it, a High Explosive Air Burst round, an Armor Piercing round and a Target/Practice round.


S&T Dynamics XK13



The weapon was apparently 22 lbs overweight and did not have sufficient anti-air capabilities (a large caliber grenade launcher with a parabolic trajectory and low ammunition count being used against aircraft?). The Korean military will instead be working with S&T on a new 40mm automatic grenade launcher to replace heavy machine guns. It will be ready sometime between 2016 and 2021.

Thanks to @uribury871 for the tip.

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.


  • PatrickPM

    Seems like most military small arms projects get scrapped these days

    • S O

      It’s been like that for a hundred years.
      The problem is that post-1990 the actual big ticket projects also developed a habit of being fruitless.

  • Vhyrus

    My guess is that the salesmen promised the suits the world in order to get the contract, and when the brass finally figured out that the weapon wouldn’t come close to their original expectations they dumped the whole thing.

    • scw

      The arm industries in Korea has questionable close tide with the government, even by US standard, that more than likely they will be able sell some ultra expensive but useless toys to the military.

  • wetcorps

    If they knew they couldn’t take aircraft with it from the beginning, and given no amount of development could fix it, why did they even bother?

    • Anonymoose

      >shooting at aircraft with .50cals and grenade launchers
      Do they still think it’s 1940?

      • S O

        Gazillions of guns of 12.7 to 40 mm calibre are the reason why no matter how much electronics equipment you put into a helicopter, using it over hostile ground in daylight is extremely hazardous in a conventional war.
        The cruise speed of a helicopter is about the same as the top speed of a late First World War aircraft, and it’s a bigger target.

        • Steve (TFB Editor)

          I doubt North Korea is using anything close to a modern helicopter.

      • RocketScientist

        “Do they still think it’s 1940?” Well most of their army exists to repel a potential invasion from the North, whose equipment is mostly outdated decrepit hand-me-downs from China or Russian. So for them, it kind of IS 1940??

    • Jonathan

      North Korean Antonov AN-2s(basically old slow cropdusters) could be used to transport KPA special forces troops behind the frontlines. I’m assuming this is what the South Korean JCS had in mind.

  • Alex Nicolin

    This XM307 clone went the way of the original.

  • Jonathan

    South Korea will be procuring forty F-35A fighters(possibly more) and three more Aegis destroyers in the coming decades. And with limited budgets, something has to give.

    The mindset of the top brass is that stealth fighters and new ships come first, infantry weapons later.

    • S O

      The F-35 is no fighter. It’s more of a light precision bomber with self-defence capability.

      • Jonathan

        No, the F-35 is a 5th gen fighter. And its payload is much less than real strike fighters like the F-15E due to its stealth configurations.

        • S O

          It’s at most a fighter-bomber, with emphasis on “bomber”. Don’t buy into the public relations hype.
          Its agility (important for dodging missiles) is on the level of 1960’s fighters, its poor transsonic acceleration makes supersonic flight near-pointless and it doesn’t bear the marks of a modern fighter in performance or equipment.

          Its focus is on light precision attack.

          • Steve (TFB Editor)

            Aircraft is not my thing, but the level of public relations/marketing done for these things is crazy. Last time I was in DC you could walk a few yards in the Metro without hitting a poster urging you to contact a congressman and tell him that the F-whatever is required.

          • If memory serves, some defense analysts surprisingly likened it to an F-105 Thunderchief on multiple levels, such as in agility relative to current-gen competitors, relative payload, and predicted casualty and kill ratios given existing and prominently employed anti-air capabilities. The one area the F-35 didn’t match up well was in price point – much, much more costly, inflation being largely irrelevant in this case.

            The Pentagon brass are looking to stealth tech as the penultimate aircraft technology, invalidating everything else from ACM to reliability rates of guided missiles and resistant to SAM installments. They won’t hear otherwise until, God forbid, we get involved in a large-scale conflict against an actual, recognized state, and F-35s start becoming $200 million fireballs across the landscape.

            This is also completely irrelevant to the post at hand, but I couldn’t resist, sorry 😛

          • William_C

            Price tag is already well below $200 million, and how is “F/A-18 level agility” comparable to the F-105? I don’t recall the F-105 having all aspect stealth either, nor the sort of sensors this thing has.

          • S O

            F-35 does neither have “all-aspect stealth” nor “F/A-18-level agility”, of course.

            The advances of the F-35 are most likely in its electronics only. Especially the DAS is bound to become standard in modern fighters soon. Too bad the packaging sucks because of the STOVL requirement.
            They should have developed one avionics package for multiple optimised airframes.

          • Whether it has F/A-18 level agility or less, it remains a hinderance – against old MiGs and poorly-trained pilots, it’ll likely perform just fine. One of these days though the rest of the world will catch on just how cheap thrust vectoring technology can be, and then the F-35 is arguably f*cked, at least at dogfighting range, which air combat ALWAYS gets down to when the scheise hits the fan.

            Newly-designed versions of the Su-27 line are being manufactured for export with thrust vectoring installed already. Not many sales, but expect those to pick up when their advantage becomes abundantly clear to those who would do our pilots harm.

          • William_C

            When it comes to avoiding missiles maneuver is second to ECM and stealth. The transonic acceleration was very poor on the C model due to transonic buffeting issues. Hopefully this will be corrected.

      • therealgreenplease

        Well said. If the AIM-120s don’t hit, it’s time to turn tale and hurry back to base. If there was ever a real dogfight against, say, a SU-27 or equivalent fourth-gen fighter, things wouldn’t pan out very well.

        • Brandon

          I don’t think anyone is expecting to dogfight in the F35 (or anything new aircraft for that matter). Stealth and air-to-air missiles are the defense against enemy fighters.
          Not saying I necessarily agree with that line of logic, but that seems to be the design philosophy, at least in the US.

          • therealgreenplease

            100% that is the philosophy, though I think it’s misguided at best. Long-wave radar and multiple transmission, single detection radar will render most stealth tech obsolete in the relatively near future.

            That said, massive F-35 cost over-runs tells me that there’s another project waiting in the wings which the F-35 has funded in a discreet fashion. Seems to be a routine thing for the DOD: pay 3x for project A publicly and end up with a public project A and a secret project B hiding out in a hanger in Groom Lake

  • allannon

    My guess is the AA capability is less “shoot at ex-Soviet MiGs” and more “shoot at ex-Soviet and/or converted civilian helicopters”.

    That doesn’t seem like an unreasonable use.

    • therealgreenplease

      Seems like something a modernized .50 cal would be much better suited for.

      • allannon

        That’s more or less what these things are.

        • scw

          Even for slower civilian type aircraft is still far better choice than a grenade laucnher.

          • allannon

            You mean like the AP round that’s developed for these sort of things?

  • Lance

    Figures like our OICW I think the idea was a little too ingenious than practical.

  • big daddy

    So it seems like not only the DOD has no idea what it is doing. Mistake #1 is thinking you can get 2 weapons to replace one. It’s more like you need 2 weapons to make one work better in a real combat situation. Hence the 50 cal and Mk19 combo. Mistake #2 is to think such a small grenade can do anything lethal at lower velocities.

    • Chase Buchanan

      What? It’s a grenade. It explodes when it hits the target, velocity doesn’t matter except for getting it there.

  • just axing

    Why is the gun on a plastic stand if it has a mount? Is that only a 3D-printed replica?