The Mud Will Always Get Through: InRange Desecrates A vz. 58

The vz. 58 is a rifle well-known for being easily mistaken for – but totally different from – an AK. Everything down to the locking mechanism, fire control group, and operating mechanism is different from the famous Kalashnikov, despite appearances. In fact, the vz. 58 rifle was a huge achievement for the relatively small country of Czechoslovakia (now the Czech Republic and Slovakia), as they had produced a weapon every bit as good as its contemporaries from the superpowers. Certainly, a gun’s merits can’t be boiled down to a simple mud test… But it wouldn’t hurt to see how it does anyway, right?

In mud, the vz. 58 suffers a familiar problem: Gunk gets into the fire-control group and retards the motion of the firing mechanism (in this case, a linear hammer striking a firing pin). Fire control and locking are the biggest vulnerabilities of any rifle in a test like this, and so the most critical factor is how well-sealed the action is at these elements.

Like with the M1 and the AK tests, a single mud test doesn’t prove the vz. 58 is a “bad” rifle, but it is an additional data point. In fact, Karl and I agree: The vz. 58 is a fantastic rifle, better in a lot of ways than the AK itself.

So far, though, the AR-15 remains the Unlikely Mud King.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • Bullphrog855

    They should do the FN2000, I don’t personally like the gun but it’s locked up as tight as it gets. Arguably to a fault. Would like to see it thrown in the mud

    • Heretical Politik

      Aren’t the ejection ports in the front open? With open slots too? I would think those would get clogged up real quick.

      • Tyler McCommon

        It has a cover over it.

        • Heretical Politik

          Interesting. I’ve never seen one up close.

          • ostiariusalpha

            I discussed this with one of the other regular commentors, Tassiebush, an excellent chap. The FS2000 is very compartmentalized, with the vents and charging handle slot area of the barrel assembly not having open access to the bolt assembly and the rest of the action. I can post up the pics again if anyone is interested.

          • Heretical Politik

            or link to article? It is a pretty interesting design.

          • ostiariusalpha

            Ha ha! It is indeed interesting, you have to give it that. I certainly enjoy shooting mine. It can take a few hours for posted links to be approved, so I’ll just tell you to search the tags at the top of the article (if your using a smart phone, you have to hold it horizontally for many of them to show), look for “mud” and follow that link to Nathaniel’s other mud test article “InRange TV Gives An AK-47 A Mud Bath – The Results May Surprise You.” Or you can just use the search bar. Anyways, you have to scroll through about a bajillion comments before you’ll find the conversation between Tassiebush & myself. If all that seems like to much work, I’m still open to just re-posting the photos.

          • Heretical Politik


          • KestrelBike

            You can post the links, but just replace the period between the domain name and designator with a literal “dot”. All the person has to do is manually copy/paste & replace back with a period. like http://www.thefirearmblog dot com/ostiariusalpha/tassiebush/interestingphotos.

          • Tassiebush
          • Jonathan Ferguson

            I don’t know about the FS2000, but the F2000’s port cover functions like an AR cover; springs open in use, but must be manually closed. It doesn’t magically spring open and shut.

        • Avery

          It’s like a little spring-loaded door that opens and closes when cases are pushed through it.

    • Kyle

      I suspect the F2000 would do very well. If I remember correctly the rifle even has a rubber gasket in the magazine well to seal it when a mag is inserted.

    • BrandonAKsALot

      I can never find the article on it, but supposedly, the F2000 exceeded all requirements during NATO testing and the only serious failure that happened was when the ejection shoot was literally epoxied closed. They jammed all sorts of debris in the tube and it cleared all that. It’s really an exceptional piece of hardware.

      I fell in love with it the first time I laid hands on it and bought one shortly after. Make that two actually. Traded the first off for a PS90 at some point. It’s still one of my favorite firearms to this day. It handles wonderfully and I’ve personally shot mine in some pretty nasty conditions including a crazy thunderstorms and ice.

      • ostiariusalpha

        Yeah, as long as you keep the toilet seat shut, it doesn’t care what’s going on outside. Mine was a bit finicky about what kind of magazines she liked at first, but once that was resolved, my lil’ tuna fish now runs like a champ. Do you have one of the aftermarket replacement pieces for the rather delicate charging handle locking toggle or has yours somehow been preserved? Did you go with any of the trigger jobs?

        • BrandonAKsALot

          My charging handle is still original, but I never lock it and slap it into battery. I actually did work on the trigger oak myself and it’s a better pull now, but it’ll never have that match break just due to the design.

          • Hyok Kim

            “My charging handle is still original, but I never lock it and slap it into battery.”

            Double feed?

          • BrandonAKsALot

            Not something I’ve experienced and I’m a little confused. I was referring to the HK slap that many like to do and was causing breakage on some FS2000 charging handles or that’s the rumor.

          • Hyok Kim

            Oh! I get it.

      • Vitor Roma

        The FN2000 looks bulky but everybody comments on how comfortable it is, and it has a similar tapped piston to the Scar with very smooth recoil. The only real complain I hear about it is the trigger.

        • BrandonAKsALot

          The felt recoil is very mild. I wouldn’t say the trigger is the worst. I’ve used way worse. It’s just meh. It’s just sort of heavy. I don’t feel the travel is super long or out of line with what’s expected in a combat rifle. I would say the trigger in my SCAR was worse in some aspects. It was gritty, heavy, and terrible.

        • Hyok Kim

          I haven’t fired it, but I handled it. It looks bulky, but it ‘hugs’ you naturally when handling it.

    • hking

      I would like to see them do as many modern rifles as they can. Tavor, AUG, Scar, FN2000, 805 Bren, etc.

    • mechamaster

      I have the picture how FS2000 will jammed :

      1. The FN2000 will suffer in the ejection port tube when clogged with thick-mud and create a friction in the spent-case, and it’s jammed because it’s clogged with spent case
      2. The ‘fine-mud-soup’ will enter the F2000 chamber via ‘chamber inspection port / trapdoor’ and create a friction between tight tolerance mechanism inside

  • I have a feeling that the AK-12 mud test will go similar to the AK due to the fact that even with the more sealed bolt/top cover it still will allow some mud to come in. Of course only a real test will determine this hypothesis.

  • Marc

    I suspect that the gunk left on the outside of the bolt was worked into the action with the first shot. In that case merely flushing the outside of the bolt would have prevented the malfunctions.

    • FarmerB

      Exactly – bolt retracted – mud stayed in place then dropped into open action and bolt couldn’t close (which will happen to any firearm on the planet). But a quick douse with some water and it would have been back in action – no disassembly required.

      • Jay

        yep. When the bolt is thrown back by the gas system, because of inertia, all the mud/wet concrete from the outside of the bolt will fall in the action in front of the bolt.

        • FarmerB


        • Tassiebush

          there’s a chance that if it were direct impingement it might blow the crap out of the way. of course there’s a chance it wouldn’t too but it’s seeming like it might be a tad better.

          • CommonSense23

            Well the AR pretty much did that.

          • Tassiebush

            Yeah it did and being sealed up more helped lot too.

          • ostiariusalpha

            When InRange did a similar test of the MAS 49/56 (an exposed bolt gun just like the vz 58), it went through its mag with only a couple misfires. The DI is very forceful on the MAS, thanks in no small part to the power of its 7.5×54 cartridge, but I’d venture having even an intermediate cartridge could blow any muck or grit away from the bolt face and kept that Czech beauty in the fight without irremediable malfunctions.

          • Tassiebush

            Yeah it seems to be second after the AR15 of all they have tested.

      • lucusloc

        “which will happen to any firearm on the planet” except the ar-15 it would seem. , ,

        • FarmerB

          No, I meant that if you get incompressible stuff on the front of the bolt no action will close.

          • lucusloc

            ah right, I though you were talking about stuff falling off the bolt onto the bolt face.

  • I love me some Vz58s, and this made my heart hurt.

    • Me too, buddy. 🙁

      • ostiariusalpha

        Maybe if it had been a DI system, it might have lasted a bit longer. ?

        • DW

          Nope, it’s the trigger mechanism.

          Give piston AR a mudbath test it probably will fare very well. Not saying piston ar is good though, it just has less holes to be violated.

      • CommonSense23

        You know of any good reading material for reading about the Vz58s. My only experience with them was battlefield pickups, and they were all in horrible condition.

  • Slobberjaw

    Keep the videos coming! Even if they do crush everything I believed.

    • De Facto

      They shouldn’t. This is junk science at it’s finest.

      • Joshua

        Have you ever seen a military mud box test?

        They are more harsh than this.

        • De Facto

          If you design a gun specifically to beat a certain criteria it will do so. I’m aware it’s a relatively sealed system, and yes, it passes a “mud box” test with flying colors, because the system was designed to pass precisely that kind of test. Criticisms of the AR have to do with it’s ability to operate in dusty/harsh conditions without cleaning. Subject an AR to a “sandstorm” test such as the AKOU uses and it won’t fare as well. Nor will a jam with an AR be nearly as easy to clear. All this test proves is that the AR keeps mud out better. Not which is more likely to fail in the field under actual use. Hence why I call it junk science.

          The VZ58’s high points are that it’s easy to clean, easy to use, and rechargeable with stripper clips. Using stripper clips means the action is more open to the elements, ergo more likely to jam if you shoot it with debris clinging to it.

          • ostiariusalpha

            InRange did a “sandstorm” test on an AR-15. It did pretty well.

          • De Facto

            The AK is noticeably absent in that test.

          • Alex Agius

            and the ak failed the mud test

          • Joshua

            When was the AR designed to pass a mud box test?

            I take it your not familiar with military trials. You submit a gun and it gets tested on all the different trials.

            You don’t get the build it on a per trial basis.

            The AKOU test isn’t a sand storm test, its a dump a handful of sand into the receiver while the rifle cycles test.

            Sandstorm tests would be to use blowing sand and the gun fired in an upright normal position.

            Have you ever actually used any of the guns you discuss? You say clearing a malfunction on an AR is hard….its not, if you practice all can be cleared in a second or two outside of something breaking, and the AR has been used in Afghanistan extensively with little to no trouble.

          • May

            Inrange subjected an AR to a sandstorm test already, it worked flawlessly.

  • ExMachina1

    Ever since they posted the AR video, these guys have my full attention. Before then I thought their mud test was too severe (essentially a “perfect storm” of grit and water). But after seeing the AR survive, I know the test **IS** passable. Would love to see a few bolt action rifles subjected to the same conditions.

  • Keith Denigan

    I’d like to see how well the FAL does in the mud.

  • May

    Since the AR took all the rounds without failure in this test, wouldn’t the only way for a gun to “beat” it to be for it to somehow fire more rounds than it actually has in it? If that’s the case then the AR is probably gonna stay the champ until they get their hands on some duplex ammo.

  • De Facto

    The VZ58 is more vulnerable due to it’s open action, similar to the Garand or the SKS. However the merit of it’s design is being able to quickly recharge magazines with stripper clips. There is no perfect weapons system, only different features and trade offs.

    • lucusloc

      I agree with this statement. This test is an extreme that will not likely be seen by even seasoned combat troops. As the test name suggests there have only been a handful of times combat conditions came close to what this test has to offer. The fact the the tests namesake is a battle that took place a hundred years ago (as opposed to more recent history) speak volumes. Yes it is good to know the limits of your weapons system, but picking your weapons system based off of only one factor is a mistake. You must pick your system based of the totality of considerations. For us civilians many of those considerations are personal (e.g. “does this gun fit me ergonomically?”). This is a benefit that militaries do not have, and means the civilian market space is much bigger (instead of asking “does this gun fit me” the military must ask “does this gun fit the Xth percentile”, which is a much more limited space). Prioritize your considerations based on what you are likely to experience, and get what works best for you.

  • UnrepentantLib

    At some point you should compare the Lee-Enfield and the Mauser 98.

  • Zebra Dun

    There are no bad rifles among those tested, there is how ever bad mud.

  • RMP52

    These “mud tests” are about the stupidest “test” I’ve seen yet. What a waste of time, you throw a firearm in a barrel of mud and wonder that it doesn’t perform, gee no sh*t! The best made gun, or about any piece of machinery, isn’t designed to work correctly while saturated with mud and grime, what a surprise.