IV8888’s Piston AR Meltdown

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Do piston guns handle heat better than DI guns? If so, why? If not what shortcomings do they have? The video from the popular YouTube channel IraqVeteran8888 embedded below doesn’t quite answer these questions, but it’s still very interesting:

The end result? The LMT upper receiver’s mechanism failed at a count of 833 rounds, suffering a bent operating rod and a heavily peened bolt carrier. For those keeping score, that compares to 830 rounds for IV8888’s DI AR-15 meltdown, 265 rounds for their WASR-10 test, and 895 rounds for their Vepr AK test. In both AK tests, the rifles were stopped by mechanical failures (misalignment of the gas block and piston), but the DI AR-15 suffered a catastrophic barrel failure in its A2/M4-profile barrel, right at the thin-walled section behind the gas block.

The test he conducted in the video embedded above was far from a controlled experiment, but still Eric has given us a platform for rounding out discussion of different rifle gas systems and how they handle heat. The first, and most obvious conclusion is that thick-walled SOCOM- or HBAR-type barrels provide a considerable advantage in long strings of full auto fire. This is not news to folks familiar with the literature, and is the reason the excellent 14.5″ SOCOM-profile barrel now being fitted to every US Army M4A1 Carbine was designed in the first place.

Setting aside the AKs for the moment, what can we say about the performance of operating rod driven AR-15s versus their direct gas impingement counterparts? Well, generally speaking, not a whole lot, but the LMT upper did exhibit a failure mode that has been the Achilles’ heel of operating rod guns since before the 20th Century: Bending.

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A bent operating rod. Needless to say, this is not a good thing for functioning.

 

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Not a good thing at all.

 

In the twilight of the 19th – and the dawn of the 20th – Century, the gas operating rod mechanism was not well liked because the metallurgical and manufacturing limitations of the period made long, thin operating rods impractical for a standard issue weapon. If not made right, they would bend and cause the weapon to stop functioning, and making them correctly was for several decades too costly for individual weapons. When John Garand designed his famous rifle that became the M1, this was an area of prime contention for his critics, with many calling his design “impossible to mass produce”. Garand circumvented these problems through clever design and engineering of many novel manufacturing tools, but still, cockeyed operating rods are a common sight on M1s even today.

Today, the problems of the early 20th Century have been largely solved for operating rod rifles, but as the LMT above demonstrated, it is still something that can happen under certain circumstances. Still, such a preventable malfunction was surprising to see on such a well-regarded brand as LMT. The firing schedule for that test was undoubtedly brutal, but without seeing a detailed scientific analysis of the failure, I’m left scratching my head. Firing a weapon fully automatically like that does stress it more, but primarily through heat, which – in theory – shouldn’t have conducted so far back to the gas piston and key. The only theory I can grasp is that the heat from the barrel was close enough to the piston to damage its rigidity, causing it to warp, which subsequently deformed the bolt carrier extension. This seems like it could be a quirk of the gas operating rod AR-15’s “retrofitted” nature; the carrier extension is small, so a strike from the piston hitting anywhere other than its direct center could weaken and peen it. Likewise, due to the small space in the AR-15’s upper receiver – originally designed for a compact gas tube – once this deformation occurs, the firearm ceases to function properly.

With a direct impingement gas tube, this failure could not have occurred, but that’s not a condemnation of operating rod systems in general, although I hope it highlights some of their possible shortcomings. Many operating rod designs, such as the numerous light machine guns from around the world, handle heat very well, mechanically speaking. It seems reasonable, though, to suggest that adding an operating rod to a formerly direct impingement design without a substantial amount of testing and an overall redesign comes with some unintended and undesired consequences, and I think this IV8888 test demonstrates one of those possibilities.


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 can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • BattleshipGrey

    The reason I switched to the AR platform is because of aftermarket and parts availability and commonality. I don’t have a FA gun (and even if I did I wouldn’t be doing these tests), but having very proprietary parts essential to the operation of the gun wouldn’t seem ideal to me.

    If I had a piston AR, I’d feel more comfortable having some spare parts. I just checked LMT’s parts store and didn’t see any of the piston components. I’m not sure how well other manufacturers do in keeping those available.

    • Uniform223

      Also understand parts commonality. You can’t take a piston from an LMT and one from LWRC and do some mix and match. With DI systems (from what I’ve seen, read, and heard) the gas tube (with the exception of different lengths) are pretty much universal. You can take a gas tube from a Colt and stick it into a Windham and it should work.

      • BattleshipGrey

        Exactly. At the moment I’m too lazy to check other companies to see if they sell individual piston parts, but for my money (if I were to invest in a piston AR) I’d want extras for that very reason.

  • Major Tom

    So despite the alleged “superiority” of the DI gas system an aftermarket piston conversion still lasted longer than a DI gun in a full-auto torture test? Not surprising. Piston guns have often been able to handle heat a lot better than DI guns for a given barrel length. This becomes extremely evident when using shorter barrels.

    I wonder if this test could be replicated on full-auto mil-spec stuff rather than aftermarket kitbash? Like a standard US Navy M16A3 vs a standard RGF AK-74M? Pity the global politics suck right now, we might not be able to conduct such a test.

    • Twilight sparkle

      Well you must have missed the part about the thinner barrel on the di system, gas system didn’t fail, the barrel did.

      • Major Tom

        I saw that part, the barrel wouldn’t quite have failed so soon with a piston design. Operating rods are a known heat sink when it comes to barrel heat.

        If the test had more control such as the same barrel in both cases, would it have been different?

        • Twilight sparkle

          that sounds unlikely, but either way even if the barrel wouldn’t fail the gas system still did.

          It would have been quite different, both gas systems would have failed, the gas piston would have done its thing and di would have continued until the tube burst hundreds of rounds later.

          • Major Tom

            I’m not entirely certain of that conclusion either. In a DI system the entire barrel and receiver takes the heat making the gas system and barrel heat up quicker. In a piston gun, the piston itself provides an additional heat sink on top of everything else.

            Provided both had the same quality of barrel and ammunition at the same or similar rate of fire, the DI system would overheat and fail before the piston one. It’s simple physics, more mass equals more and/or better heat distribution.

            Otherwise we’d have DI belt-feds for machine guns and no such weapon exists in this world.

          • nadnerbus

            The bolt group takes on more heat in a DI system than a piston system. Changes the equation a bit.

          • Joshua

            It’s hardly relevant.

            If you fire 270 rounds(a basic combat load) in full auto with no break, and then pull the carrier you may be looking 90°F on the bolt and 100°F on the carrier.

            That’s vs 80-90°F on an op rod AR carrier.

          • Twilight sparkle

            The bolt carrier acts as the piston in the di has system (which we should acknowledge is actually a gas piston and not true direct impingement) so the bolt absorbs a lot of hot gas that would be contained around the barrel of a short stroke piston system.

            Using your same logic of more mass = better heat distribution the di system still wins because of the mass of the bcg which is integral to its gas system, the short stroke piston does not have that same advantage because it’s gas system ends on the operating rod that just pushed the bcg.

            Again we should acknowledge that what we’re calling direct impingement isn’t really direct impingement, it’s just a non traditional gas piston.

          • Major Tom

            You are aware the BCG still takes the heat in a piston system right? The heat that would strike the operating rod transfers into the BCG via conduction and convection. It would take a lot longer for the BCG to reach the same temperature in a piston system than it would for a DI.

          • Twilight sparkle

            It really doesn’t and thats supposed to be the magical benefit of a short stroke piston, it keeps the hot dirty gasses out of the action and instead lets them linger around the barrel. Try rewatching the future weapons episode about the Hk 416 and come back about how the bolt absorbed heat.

          • kzrkp

            “he heat that would strike the operating rod transfers into the BCG via conduction and convection”
            this is complete nonsense

          • The piston is a heat sink now? Buddy, if your piston is heating up like that, that’s bad. How is a DI gas tube not a heat sink, either? For a given mass of operating parts, the DI tube should actually make a much better heat sink since it’s not under a compression load and can operate over a wider dimensional range, and could therefore distort under heat more without failure.

            At least, in theory anyway.

            Belt fed MGs don’t use DI because it’s not a good match for quick-change barrels, primarily, not because it can’t handle heat as well.

          • Kivaari

            Reality is that under conditions found in the real world no one would fire that many rounds in such haste. This is fun as a simple demonstration of how hot the rifles got. Beyond that it has no scientific value. I certainly would never expect any rifle to be abused in such a fashion. Since the gas tube on ARs last in excess of 10,000 rounds, we should not be worried. The likelihood of a gas tube failing is considerably less than the piston-rod and bolt carrier on rifles like this one will fail before the simple tube of a DI gun. This video shows the weakness of the piston guns.

        • Um, I think the lighter profile of the DI gun’s barrel was the reason it failed at 830 rounds.

          The oprod gun’s mechanism failed at 833, though exactly why is not clear. Not a ringing endorsement of oprod guns, exactly.

          • mosinman

            not to mention the last 3 were a single shot.

        • Kivaari

          I guess I can’t think like you. I can see the government profile barrel failing at the same round count regardless of having a DI or piston system. In the earlier shoot, the barrel was the issue. How a piston gun corrects the failing barrel buzzes over my head.

        • Kivaari

          BUT, this was done for the fun of doing it. It certainly has little value in the gun fighting world. Even in military settings, needing to use FA has its limits. A typical fire fight might see you dumping a magazine into a close range threat. Like breaking contact in an ambush. Just doing one mag dump after another means you are simply wasting ammunition. Perhaps it would be better to try to out think the enemy before you melt your rifle.

      • TVOrZ6dw

        Exactly, the previous test used a different barrel. I would like to see the DI test redone with the same heavy barrel as this test. The DI system didn’t fail, the barrel failed on the previous test.

    • Doctor Jelly

      Three rounds difference in over 800 is statistically insignificant. For the purpose of comparing the two tests, round count is equal at the point of functional failure. Instead you have to look at what failed and why:

      DI: Barrel melted, but has less mass than piston variation. The operating system did not fail.

      Piston: Rod likely overheated and structurally failed when load (pushing the bolt) was applied. Barrel has more mass that DI equivalent and the operating system itself did fail.

      As to mass of the piston sinking excess heat, this is likely why the system failed. If the piston had more mass, it would likely last longer. Just as if the DI setup had an equivalent barrel to the piston one, it would have more mass to sink heat. The DI system as well inherently will sink some excess heat since it is porting hot gas away from the barrel and into the bolt.

      With all things equal (which these tests are not), and taking into account what actually failed (giving consideration to the barrels), it would appear that a piston AR is actually more likely to fail in such an extreme test.

    • ostiariusalpha

      This may have escaped your notice, but the barrel on the internal piston AR that the IV8888 crew torture tested was stainless steel, which does not handle long strings of sustained fire as well as the chrome-moly barrel of the LMT op rod rifle. That is the one, and only, reason the LMT lasted slightly longer; chrome-moly barreled, internal piston guns can go much further.

      • MANG

        “Much further”? We’re all speculating and arguing about the number of angels on the head of s pin. That stainless v. Cromo shade means nothing until it’s verified.

        • Doctor Jelly

          I know little about the actual content of alloys (and what additions in what quantities affect which properties), but I can see where his thoughts are coming from as I’m sure molybdenum has a higher melting point. The problem being that they’re both still steel alloys which are primarily comprised of iron. As such they would maintain moderately similar melting points.

          Quick Google search says (melting points):
          Chromoly: 2610°F
          Stainless: 2550°F

          Looks like it may make some difference, but I doubt it would be statistically significant…

          • Paladin

            Actual melting point isn’t really all that important, since the barrel would fail long before any part of it reached those temperatures. What matters is how well the alloy retains structural strength as the temperature increases.

          • ostiariusalpha

            Exactly.

          • Precisely.

          • There are other reasons outside of melting point.

            Specifically Stainless is not as good at abrasion resistance, heat exhaustion, and anneals differently.

          • tts

            Vuurwapenblog did a interesting post on this subject several years ago and can be easily googled by searching for the article’s title: “Barrel Factors for Small Arms Nov. 10 2009”. Not linking it since my post would end up stuck in moderation.

            He links a bunch of great .pdf’s from previous destructive tests done by the military back in the 60’s, 70’s, and 90’s that are relevant to what you’re talking about.

            Anyways a key bit of data he mentions is this: “We also see this in a destructive test of the (heavy barrel) M4A1 versus the (lighter barrel profile) M16A2 – although both barrels failed at approximately 1600F, it took longer for the M4A1 to reach that temperature.”

            That bit of information is from a mid 90’s destructive testing paper so I’m not sure if its applicable to today’s barrels which might be better made but at least can serve as a means to illustrate how different barrel failure temp can be from metal melt temp.

          • The material is the exact same. It has not changed over time.

          • tts

            Can you say if the barrel failure temp is still the same then? I’d assume so if the materials are the same but that is just an assumption, I’m not a metallurgist and have no clue if there are any possible manufacturing differences that might come into play.

  • Tyler McCommon

    They really need to do an HBAR DI test next.

    • Agreed. We have always been ready to provide an HBAR for testing.

      • Wolfgar

        I would gather to guess your barrel would outlast the other components. You make some great barrels, my favorite.

        • It would in HBAR form. Barrel thickness is critical with full-auto firearms.

          • Drew Coleman

            It’d be interesting to see a full gambit of tests on different barrel lengths and profiles – like a 10.5 inch for example.

          • Would be fun!

      • Harrison Jones

        Wasn’t your pencil barrel used for the DI test? It was supper impressed by the performance from such a slim barrel.

        • Our Government profile in stainless steel. The barrel was quite thin compared to the HBAR shown above.

      • Solace Greer

        Have you run any stress tests on the ARAK-21st century upper?
        I bought one of those with a Heavy 16″ 5.56/.223 a while back and am curious how badly I can abuse it without breaking it.

    • Laserbait

      Logically, they should have done an HBAR/DI test before the piston gun. Then if/when the gas system fails, switch to a piston design.

    • Joshua

      It’s been done. Colt released a M4 vs M4A1 video to washing times after the whole Wanat fiasco in the news.

      I actually went and added it all up and the M4A1 expended 870 rounds in 4:20. At that time the gas tube blew and the gun became a bolt action AR.

      So it fired more rounds, in less time than this gun and made it a few mags longer.

      • Uniform223

        are you talking about this one?

        • Spencerhut

          Must have actually been in AK in some sort of super stealth AR looking camo. Everyone knows AR’s can’t make it through more than one or two mags without malfunctioning or exploding.

        • Joshua

          Yep that’s the one.

      • ostiariusalpha

        It’s actually 911 rounds before the gas tube bursts.

  • HKmaster

    Time for another piston vs DI flame war…

    • DW

      Relive the good old days of 2010?

  • Spencerhut

    The barrel failure of the DI gun is an easy fix with readily available
    common spare parts. Common spares, this is the main reason we have stuck with all DI
    guns, at least for now. If there ever is a “standard” agreed to in the
    piston market I’ll try one out. We have avoided the “government” profile and pencil thin barrels for durability reasons. Even running an AR class where you only burn through 1,000 round in a day, having a bit heavier barrel is a good thing.

    • kzrkp

      the barrel failure of the DI gun is because it was a government profile barrel and it drooped at the lightening cut, where as the piston gun had a HBAR profile and failed hard at the piston.

      I wouldn’t call a barrel a common spare part, unless you want to give me some free barrels lol

      • Doctor Jelly

        The implication isn’t that they’re growing on trees, but that they are easily obtained and readily available at multiple outlets due to the exceeding number of AR’s in the public’s hands. The op rod version will likely only have parts available from the manufacturer as there is not a very large base of these firearms in use.

      • Spencerhut

        The only part of an AR not a common spare is the lower. Every other part is simple and common.

    • Kivaari

      In high use environments the HBARs have value. For everyday carry, and little shooting, the light weight barrels are more fun to carry. Most of us will never fire the rounds needed to ruin an AR. Only in military actions would the heating be an issue. It is nice to see how well the ARs function.
      A few days ago on one of our cable channels showed training in Kurdistan. The instructor was finding that many of the AK rifles were non-functioning. It was quite a show to see him and students trying to fire rounds, only to have the guns simply not perform. In short order it looked like over a dozen AKs were on the ground after failing. Why, was never explained in the video. It certainly was the first time I ever saw AKs fail like that.

      • CommonSense23

        AKs fail all the time. The issue is most people don’t shoot them enough cause issue. You put them in a high round count training program, they start having all the issues any other gun would have.

        • Kivaari

          As far as the commercial guns, the only ones I’ve seen fail were the Chinese in .223. I remember that this was shown on National Geographic Channel. What was interesting is just how could so many faulty rifles accumulate in one spot. As simple as the AKs, one would expect a quasi-government militia would have repaired them before sending them to use as training rifles. Basically, there is very little ever needing to be repaired on AKs or ARs. Simple parts pull and replace should have made the rifles fully functional. The commander of this unit should have been doing some azzchewin’.

          • CommonSense23

            The U.S. military can’t even maintain the vast majority of its small arms. Why do you think people complain about the M9, M4, Saw. As much as I hate the M9, it’s a good pistol. The M4A1 is world class. And the Saw has been plagued by a horrible maintenance in the service. You hear about people complaining all the time about those weapons. Its not the design that’s the issue, it’s the maintenance programs.
            And that’s the thing, put AKs in a western training program, and you will start seeing all the same issues the M4 faces. The vast majority of people equate cleaning with maintenance, which it isnt.

          • Kivaari

            I would disagree. Yes, some units fail to keep every piece of equipment properly maintained. That was shown in the Icord hearings on the Vietnam era M16. That led to the M16A1. But, failure to keep your gear going comes down to how command treats the issue. Have the troops clean their rifles and such and you wont see many problems. Except for rough handling the rifles were kept up well in my unit. I don’t think we would see many failures regardless of which M4 or AKM was handed to our troops. Both systems are excellent, for what the end users wanted. Soviets didn’t want anything better than the AKM. Americans want better, and we got it. OK, the M249 is a disaster. My kid was issued one while in Iraq. While there he never fired his machinegun in combat OR training. While stateside the M249 gunners did not like the gun.
            But, keeping the guns clean was demanded by the sergeants who answered to the O-rates. If middle management doesn’t do its job and the bosses up the chain of command you will see lazy soldiers doing as little as permissible. Each soldier needs to care for his weapons. Some people care. It is all about attitude and authority permitting substandard performance whether its a rifle or tank.

          • CommonSense23

            Cleaning a M9, a M4, and a Saw is not real maintenance. Its the replacement of wearable parts before they fail/break that is the issue. And the US military is absolutely horrible about it. Ask the end user what maintenance they are allowed to do on their rifle or machine gun, not cleaning but maintenance, replacing of parts, inspection of wearable parts. True maintenance of firearms in the US military is a absolute disgrace.

  • Twilight sparkle

    Man I just checked my piston guns and my m1 garand also has a bent operating rod.
    Oh wait… it’s supposed to be like that.

    • Yep, it has a dogleg to it by design, but they often get warped. Mine is.

      • Twilight sparkle

        That’s no good, I would imagine the bent nature of the design could make it prone to causing those issues with torque since it’s not linear. Hopefully yours isn’t beyond repair.

        I’m aware of the dogleg, I was just making a joke because the bent ar piston reminded me of the first time I saw a garand piston.

        • Mine’s not really gooned up, it’s just bent a bit. The Garand’s not that sensitive to oprod bending, I think, but it is prone to it.

          • Twilight sparkle

            I feel like a lot of issues with garand op rods are probably cause by graduates of the Wild E. Coyote School of Gunsmithing that think they need to straighten theirs.

          • ostiariusalpha

            A lot of the issues with Garand op rods are caused by people that don’t realize that you can’t just fire any type of .30-06 through the gun and not expect problems. They have a very selective range of loads that won’t damage the gas system and action.

  • Sam

    I wonder if a long-stroke piston like a PWS would fair any better or worse. There’d be no peening on the bolt carrier… but PWS does use a two-piece op rod.

    Somebody donate one to his channel.

  • John

    I want to see an HK416 10.4″ upper get put to the test instead of a LMT. Even a MR556 would fare better than the LMT if I were a betting man.

  • ostiariusalpha

    Another interesting video from Eric and the IV8888 cohort, and an excellent follow-up and assessment from Nate! Of course, one thing that shouldn’t be glossed over is the type of steel both barrels used. The stainless steel of the Faxon barrel on the “DI” AR rifle generally gives better precision and longer throat & rifling life on semi-auto, but it was never intended to withstand the heat of full-auto like a chrome-moly barrel can.

  • Michael R. Zupcak

    This is what I want from TFB: A poll for “Best DI AR-15” and one for “Best Piston AR-15”. Once the poll is over, do a side-by-side test of the two winners.

    Contenders for DI would probably be KAC, Noveske, etc. Piston contenders would likely be LWRC, PWS, H&K MR556 and maybe Adams Arms.

    Only true AR’s would qualify, so something like the Faxon ARAK or Sig MCX would NOT be considered an AR despite fitting on a milspec AR receiver.

    • Sam

      I have a PWS, and I chose that over other options almost exclusively because of the long-stroke piston.

    • Tassiebush

      I think a few more sign ups on Patreon might be needed to support that one

    • Couple of problems with that:

      1. Favorable popular opinion does not mean a gun is the best. For example, I know that for the piston category, the HK416 would win, hands down, if you polled people. Name recognition and vidja gaymes and all that. Is it the best? It’s not bad, but I can’t say whether it’s the best.

      2. It would be more important to make sure that the guns were as identical as possible, not whether they’re the best in each category. Consider, for example, that the HK416 probably has a stronger set of springs and higher operating group velocity than some of its competitors. So if it works better on a short course of fire, is that because the piston improved functioning, or because HK made some changes unrelated to the piston that improve performance in those parameters? (By the way, overgassing a gun and strengthening the springs can improve functioning when dirty or in debris, but it also wears the gun out faster. Is that an “improvement”? Depends what you want, I guess.)

      3. Such a test would be very, very expensive, unless it were sponsored. I think that’s unlikely.

    • jono102

      What would be an even more entertaining would be a thread where only those with experience with the discussed platforms could post comments. Anybody else would be “Read/Info only”

  • Bill

    If you want a piston gun design a piston gun. Does anyone think you can adapt a Chevy transmission to a Ford engine?

    More importantly, given sufficient abuse, ANYTHING and EVERYTHING will fail.

    • Gizmo

      Powerglide

      • Cap’n Mike

        Ford 9 inch

    • “Does anyone think you can adapt a Chevy transmission to a Ford engine and come out with a superior powertrain?”
      Yes.

    • Anonymoose

      Yeah, we need some SIG556, SCAR, and ACR meltdowns.

    • 1911a145acp

      By my observation dropping a Chevy engine in generally improves things dramatically across the board……

  • NewMan

    H&K is the only one that make proper piston AR. Everything else is junk.

    A 416 can easily beat this test without breaking a sweat

    • randomswede

      Could you link me to the video because I haven’t seen it?

      • NewMan

        The fact that the 416 won the Marine’s IAR competition should tell you something.

        • randomswede

          It does tell me abit about the IAR version of the 416 and H&Ks ability to manufacture, but nothing about “Everything else is junk” or “…easily…without breaking a sweat”.
          I’m not saying it can’t pass the 900 mark, but from where I’m sitting it sounds like you have some kind of documentation to support that it will hold up to a substantially higher round count than 833 that this “junk” managed so; I’d like you to share this.

          • NewMan

            LMT piston guns do not have anywhere near the same level of testing and adoption as the 416. All the other piston ARs in the market only exist because they’re flavor of the week and wish to copy the 416 but most of them failed to do so.

            A properly made piston AR (like the 416) easily stomp any DI guns.

          • Uniform223

            “LMT piston guns do not have anywhere near the same level of testing and adoption as the 416. All the other piston ARs On the market only exist because they’re flavor of the week and wish to copy the 416 but all of them failed to do so.

            A properly made piston AR (like the 416) easily stomp any DI guns”

            do you have any real evidence (operational analysis or other wise) that actually proves your claim or is that your “professional” opinion.

          • NewMan

            the Colt IAR (a DI gun) got stomped during the IAR trial.

            LMT “piston” gun is just another poor attempt to copy the 416, and failed.

          • CommonSense23

            Where do you get that data from?

          • Uniform223

            spoken like a true CoD Team 6 Operator…

          • Sianmink

            Yet the military doesn’t want them because they do not run well with a suppressor.

          • mosinman

            *citation needed

          • CommonSense23

            How much time do you actually have with a 416.

          • randomswede

            Again, I’m not saying you are wrong but: I’d like to see a definition of “junk” and “easily” as well as learn your source.

            You make it sound as if you know that an HK416 will fire more than twice the rapid fire rounds over, let’s say an M4A1 as a DI gun. That would be my definition of “stomp” and “easily”; so ~2000 rounds rapid fire.
            As for other piston upgrades/versions for the AR-15 for them to be “junk” from a “melt down test” perspective I’d probably define that as 1/5 of the performance (for the sake of argument) so that’s 833*5=4165 rounds or 138 30-round magazines rapid fire.

            TL;DR: You are using, to my “ear”, emotional language in a fact based discussion and have offered no data backing your claims.

        • mosinman

          yeah that says its a good weapon, that doesn’t mean its amazing on constant full auto. i’m also pretty sure there are differences between the M27 and the 416

          • Frank

            Yes, a bayonet lug and aftermarket accessories…

    • 1911a145acp

      At 3 times the cost and 1/3rd more weight….YOU will definitely break a sweat….

  • randomswede

    As a Swede I’d love to see an FNC meltdown test, not that the FNC and AK5 are identical but good luck finding an AK5, 1000 rounds AND someone willing to film the rifle being destroyed.
    If memory serves the manual states that after 90 rounds (3 magazines) of rapid fire you are to “hook” the rifle open and leave it to cool, preferably in the snow. I recall thinking; “that’s exactly what I’ll do right after feeling the need to dump three mags in a row, have some quiet time.”

    • Scott P

      Yea AK5’s are unavailable in the states and FNC’s go for big money here. Considering how rare they are and banned from import unless as a parts kit I don’t see FNC owners wanting to destroy their irreplaceable gun they paid out the ass for.

      • randomswede

        I understand a full auto FNC is on the cheap end of full autos so it’s _only_ new-car-money or so… …and the upper is the serialized item if memory serves so when it does break it is likely to do so in the irreplaceable part of the rifle.
        Still, I’d like to see it and wishes are as free as they are stupid/silly. ; )

    • Dave Y

      Though I have not, nor will I conduct a meltdown test on my FNC I did campaign it at one of the Thunder in the Hills machine gun shoots. over the course of 8 hours, my friends and I fired just north of 3300 rounds through it without any cleaning.
      At somewhere past 2000 rounds, we had a failure to fire 2nd/subsequent shots ( that is, it fired semi-only). It turned out the sear pin had walked out of one side, loosening the auto-sear. The gun was still firing, just not full auto or 3 round burst. We pulled it from the line, reseated the sear and got it back on the line. It wasn’t as easy as it sounds, it took 4 hands to get everything lined up, but we did get it working in about 20 minutes. I used duct tape on the receiver sides to prevent that from happening again for the remainder of the shoot.
      At ~2600 rounds ( no oil, no cleaning) we had the 1st malfunction, a failure to feed. We flipped the gas valve to adverse and shot the remainder of the shoot that way, including the night shoot.

      some intangibles. It was late spring, and warm enough for short sleeves, but not hot. During a period in the early afternoon we dumped consecutive magazines through the gun in several team sessions. By the 3rd rotation of magazines, the gun was so hot, it was prohibitively painful to pick it up / hold the hand guard. Even with gloves.

      I still have it with the same barrel and it still shoots around MOA with 55 grain FMJ.

      some knocks:
      ergonomically, the gun is a bit portly for a 5.56, but not prohibitively. The selector is actually worse than the AK selector. because of the import ban, parts and aftermarket availability is minimal. I broke the charging handle of all things last year and had to source a replacement – a SCAR part, ground down worked. The original sheared off at the range. The gun had the bolt rearward with the broken off handle holding the bolt back. I cleared it and unsurprisingly, the bolt cycle with the assistance of a small screwdriver . I didn’t continue the range session, but I suppose I could have…

      The most I’ve ever ‘dumped’ from the FNC is ~330 rounds. I don’t go for the big drums or extended mags. for more than 30-40 rounds, that is why God made belt fed machine guns.

      • randomswede

        Thank you for sharing!
        The Swedish Army, supposedly, had a batch of infantry conscripts only clean the barrels for their entire 7.5 months of training without any problems of note even when/after using the very dirty blank firing ammo.

        I was a Signal corps conscript so I spent, nearly, all my time with the rifle on my back much like a complex barbell so I’m very fond of the folding stock and can’t see how one would do without.

        One of the changes from the FNC to the AK-5 is the fire selector, they opted for one very much like the one on the G3 (AK-4).

        I have a vague memory about using the tip of a round to run the bolt if the bolt handle is lost or broken and in combat of course. Maybe I’ve made that up though, who knows with human memories.

        If you still have the pieces of the original handle a machinist should be able to turn one from tool steel for not an unearthly amount of money.

        • Dave Y

          Thanks Swede. The SCAR handle is 99% the same, but it has a longer slot. Easily ground down to “FNC” length, and it’s readily available.

          I haven’t shot the FNC folder, but I test shouldered both and bought the fixed stock FNC, it felt much more comfortable.

          • randomswede

            For a sport shooter or even a frontline soldier a fixed stock probably makes more sense, I’m thinking it’s a function of time spent with rifle in hand versus on back/chest.
            I did find standing guard or patroling with the rifle in front and right hand on the folded butt gets the weight in close and manageable but almost no time is lost shouldering as it’s still one motion.
            I’m guessing that won’t work with a left side folder for a right handed shooter though (and vice versa).

          • Kivaari

            An adjustable stock, ala M4, has value as it can conform to the thickness of your gear. If you don’t have that concern a short A1-length butt, like the Magpul stocks. I like the short stocked AKs and the M16A1 length. When a “European-NATO” length stocks are used they are very awkward for most users.

          • randomswede

            True that, I think my mind went to cold war frontline soldiers who don’t spend much time in vehicles, come in varying sizes or wear body armour.
            Slightly taller than scandinavian average my preference is naturally inverse to yours, but an M4 provides for both of us.

      • Bill

        Short of the zombie apocalypse, I cannot imaging having to fire 3,300 rounds a day through anything that’s man-portable. IIRC correctly, the .mil load out for an infantryman is 300 rounds, and I go out on (LE) calls with 60 to 120 max, not including the mag in the rifle. I couldn’t lift 3300 rounds.

        • Kivaari

          While doing stakeouts I would carry 60 rounds in the MP5 or M4. The magazine pouches is where I put two radios and spare batteries. If we each fired 60 rounds of ammo in the shoulder weapon, it left us with three loaded magazines for the Glocks and 5 rounds of .38 in the M642s. That should be adequate for civilian law enforcement. It was more important to keep the communications gear going.

          • Bill

            In my light chest rig I normally have 2 30 rounders for my rifle, and the other two pouches carry a radio, cell, light, spare cuffs and expandable baton or TASER. And protein bars. Eventually I’ll either try to snack on a mag or speed load a Clif Bar.

          • randomswede

            I’m thinking there’s more ammo on hand behind a “In case of North Hollywood shootout, break glass” kinda thing?

          • Bill

            If the LAPD had had rifles on the scene at that time, there would have been a lot fewer rounds fired.

          • randomswede

            I’m very “fond” of the scene in the movie about the event where the police officer sent to a gun store to get guns and reacts to the effect of “you mean anyone can just buy an assault rifle [that’s crazy]” then proceeds to “requisition” all the AR-15s they have on hand and drive away with a trunk load.

          • Kivaari

            Yes. With back up often under 1 minute away. If it were in an isolated site, like a pay off for a drug deal out in the bush, I’d pack quite a bit more. If the scene doesn’t allow for your over-watch, it was pack enough ammo – just in case. It also involved wearing a much higher level of body armor.

          • Nobody who survived a firefight ever stopped to say “Gee, I brought too much ammo”, but every single prepper I’ve ever seen packed too many magazines in his bug-out bag.

          • randomswede

            Isn’t “too much ammo” defined as: you are unable to perform the set mission and/or more ammo than barrel life and/or more ammo than needed to shoot yourself out of an unsurvivable situation.
            Ergo, if it fits in a bag along with your “mission gear” and you can still, I’ll say run but move, you are golden.

          • I dunno, I’ve seen a lot of BoBs that were basically all magazines, water, and powerbars, with little to no medical equipment or other necessities.

            You need like, 3 mags tops, for that kind of setup. Even military forces that pick fights and sustain them don’t recommend more than about 7.

          • randomswede

            So, not really any “mission gear” then and thusly too much ammo or one could argue not enough understanding of the “mission”.
            As for medicinal gear, I see some strange thinking there, such as people who expect to make it on their own and pack a tourniquet. I imagine them sitting under a tree missing half an arm with a tourniquet on thinking: “What now?”.

            A friend who did some UN work in Kosovo and Liberia carried ammo to the motto of “Better to have, and not need, than to need, and not have.” Google tells me this is a Kafka quote, who knew.

          • Kivaari

            That’s a good point on medical gear. I keep a standard USGI aid kit without the IV liquids, but lots of bandages and compresses. When I needed the kit, I found that even a well stuffed aid kit becomes much lighter as lots of stuff is needed to first control the bleeding and more to treat the wound over the next few days. Even wound care at home following a surgery for a family member used up piles of medical stuff. One failed surgery on my self, by a surgeon of questionable quality, used up boxes of feminine pads to control the bleeding. When I was repaired a year later, that surgeon knew his stuff, and I used only a handful of after care materials. Between two surgeons, with top tier training, the wounds can be very hard to manage. Now put that into a survival setting, and I’d likely have died for want of supplies. BUY and maintain lots of medical gear and OTC medications. It’s not like the old days when we could get our family doctor to write extra pain killer Rx’s just for the aid it.

          • randomswede

            I’d like to add: train with your medical gear!
            I hear bloody hands and blood loss makes instructions hard to read. It’s also one of those skills that no matter what happens to our society(ies) will be useful, a slip up with a kitchen knife is a bleeding that needs to stop.

          • Kivaari

            AND know that simple techniques can save a life. Like elevating the feet of a stabbing victim or clearing an airway. Two vey simple things to do, that many people don’t know. I’ve used them several times, especially the airway management.

          • randomswede

            I’m not much for the “nanny state” but I truly believe that if the TV and movie industry were obligated to show some of those basics performed by those who are supposed to be medically trained we’d see positive effects fairly soon.
            I don’t think I’ve ever seen anyone elevate the legs on a bleeder and I have it hammered into my reptile brain to get the bleed higher than the heart along with the legs especially, the one big exception being if you suspect head trauma.
            Another skill that should be taught once a semester in any school anywhere is applying a first aid, again; it’s not hard you just need a basic understanding to give someone hours instead of minutes before they need more substantial aid.

          • Kivaari

            As much as I love the books by A. American and James Rawles, the need for huge piles of ammo isn’t really a needed thing. OK if the “war” goes on for many years, it pays to have lots of ammo. But, I don’t see such events happening. If we had a very nasty natural disaster or the EMP mess popular in the survivalist press, I’d like tens of thousands of rounds scattered around. People would do well to conserve as much ammo as possible. We should avoid events that would use up hundreds of rounds. Like most shootings, if it isn’t over in 5 minutes, it has really gone south on you. It would be time to deass from the contact. Break contact and run like hell.

          • Kivaari

            I agree with that position. I look at things more from a civilian police and private citizen. I my short Army NG stint, I was an armorer. I’m was not a front line soldier. If I were, then as much ammo as your can carry is worth having. Few police gun battles go as poorly as the North Hollywood affair. Once again the backwards thinking in LAPD made the fight go wrong from the get go.

        • Dave Y

          DO.
          MORE.
          PUSH UPS ! 😛

          Let me just say that 3k .223 is a lot lighter than the 5500 rounds I took for my 1919 to another shoot.

          at Thunder in the Hills, I drew a lane next to some MG38/42 enthusiasts. I thought they had a lot with 6 belt feds. Then their truck of ammunition arrived. They were an hour just unloading ammo.

        • gabriel brack

          We only ever loaded out with 210 or so. If you were lucky enough to be able to snag some extra. Generally by breaking up the left over sections of 249 belts.

        • randomswede

          I think you are underestimating your strength or overestimating the weight of ammo. : )
          110 loaded 30 round “GI” magazines makes a bit more than 110 pounds (or 50kg) and should fit in a backpack so it’s doable.
          Having said that, I totally agree with you, if you have to carry that into combat you or someone above you is doing something wrong.

          • Kivaari

            50 Kg times 2.2 pounds is a bunch of ammo.

          • randomswede

            110 even ; )
            Indeed it’s a resupply run for 10-20 people, but my point was that most… OK, lets say many adults can move it.

    • Harrison Jones

      I don’t want to see that happen to one on the NFA transferable registry. But I’d love to see it happen to a post dealer sample.

  • Adamn

    IV8888 can you try out the ACR, SCAR, Tavor and SIG MCX please? Wonder how these wonder guns handle handling.

    BTW Could you make up a more realistic scenario than melting down? 48 hrs post defense? Break contact drill, 24 h E&E, than another contact?

    • Stupid question – how available are FA SCARs/Tavors here in the states?

      • If you’re an SOT, then they’re available.

  • USMC03Vet

    The real debate after was who was picking up all that brass….

    • mosinman

      * steel 😉

      • Joshua

        Get the magnet!

  • Don Ward

    Another IraqVetAteAteAteAte video?

    Freakin’ pass.

  • SirOliverHumperdink

    Hi Point Carbine meltdown test. Now.

    • Kivaari

      Why bother? Pot metal guns, regardless of maker, are still pot metal guns.

      • tts

        Its almost certain it’ll fail quickly but to my knowledge there isn’t anyone who has done it so we have no hard numbers to point to. Just guesswork at this point.

        • Xanderbach

          10 round magazines… Nobody wants to load all those mags.

          • SirOliverHumperdink

            If I had any say at hi point, I’d get a glock mag model out. Their sales would double if not triple

          • Kivaari

            Yup!!! Hi point magazines are very low quality. Whoever did the cosmetics of the HP guns, simply doesn’t have an once of artistic gun making. The guns just ooze ugly. Had they spent a little more time making them look like pistols you would like to own, the sales would be much higher. Having a Glock magazine and good looks would be major step up from institutional ugly.

          • Lt_Scrounge

            They are rated as highly reliable. Ugly as sin but reliable, throw away affordable, and with a lifetime warranty. Not something that I would want for myself, but in a shtf scenario certainly suitable for trade or handing to a buddy who’s otherwise defenseless. If you have to outfit a family on a budget, 4 High Points for the price of a Glock is a consideration.

          • Kivaari

            I would buy Glocks instead of Hi-Points. Since we could have been buying Glocks over the last couple of years, we would be able to arm the family. Our buy good quality used handguns. I’d rather have a plain S&W M10 over two new Hi-Points. Pot metal guns hold no appeal to me. Same with rifles. I’d rather spend more upfront and acquire good guns over a matter if months. For some people buying a HP as a temporary gun may make sense to some.
            For the price of 2 HPs, I could buy a better pistol.
            A new HP carbine will not give me a gun I would have confidence in. I’d take a used M98 Mauser over any of the pot metal guns. Since we don’t know when the collapse will happen, start buying good guns now. By the end of the year a person should be able to have at least one good handgun and rifle. Perhaps a HP in a bury tube wouldn’t hurt to have. I’d just as soon put a $300 used handgun and a $150-200 surplus rifle in a tube. I would hesitate to use guns or ammo as trading stock. Arming a potential enemy could be an issue.

          • Lt_Scrounge

            There are a lot of people who don’t have the option of buying $400- 500 handguns for everyone in the family. God knows that I have been broke before. For those people a High Point for three people is better than a Glock for one person. I agree with the idea of buying used guns to save money. I’ve made out like a bandit on police trade ins. Most of them are barely broken in and have night sights. One of my favorite pistols is a Beretta 84F with trijicon night sights that I got a few years back with 3 – 13 rd magazines and a DeSantis shoulder holster for $329 plus shipping and handling. All told it came to around $400. The sights and the holster would cost over $250 alone. This past year I picked up a police trade in Glock 23 with three magazines for around $400.

            Here’s a truly scary thought for you. I shot the 4 day defensive handgun course at Front Sight in Nevada last spring with a Tristar C100 knockoff of a CZ-75 compact that I got for $259 at a pawn shop. Over 600 rounds without a malfunction or being cleaned. New they sell for around $350 at Academy sports… if you can still find them. I had my stainless full sized CZ-75 with me but that thing is heavy. If my name wasn’t a tip off, I am a major bargain hunter. My gas piston AR only cost $650 NEW delivered to my dealer. Got to love those cosmetic blemishes.

            As for buying surplus rifles, the best place to buy them went under in December when the owners got into a squabble over who owned what percentage. I wish I had known Samco Global was going under, I’d have ran up my credit card buying surplus 303 British for my SMLE. I also would’ve snagged one of those .308 conversion Spanish Mausers.

          • Kivaari

            Having a lifetime warranty is often a signal that the product will fail, but we will fix it, every time you send it in. I’d rather have a pistol that simply works and doesn’t need to be serviced. Would you rather have two High Point pistols that need repair or one Glock that doesn’t? It pays to have been buying better stuff already. Unless you just turned old enough to be buying handguns, the rest of us should have saved up a little and bought higher quality used pistol from a reliable company. Two new HPs will cost over $300 plus magazines. One good used Glock should be available for about the same price. Save up and buy the best you can find so you wont end up wishing you had spent more originally. It’s the buy once and cry once routine.
            After owning two gun stored I can assure you that trying to move people to better products isn’t for profit. It is stress reduction for both the customer and seller.
            Now I had a KIA sedan, that needed 4 sets of brakes by 14,000 miles. I should have bought a Honda. Same with guns, a “good price” doesn’t always bring a good gun with it.

          • Lt_Scrounge

            I want to find out what kind of brakes they put on my Pontiac Vibe. I’ve got over 135,000 miles on them and they still are not making any noise. I’ve pulled the wheels off routinely and they are showing virtually no wear. I drive 35,000+ miles a year for work so it’s not like it has taken me a decade to put that kind of wear on them. I got it in May of 2012 when the company took away the company car. Of course it is a five speed so I save wear on them by down shifting.

            If you’re going through brakes that fast, perhaps you should look at getting better quality after market brakes. Not the cheapies. They aren’t work the money. Get Raybestos.

          • Kivaari

            About 2/3rds of those miles were taking it in for warranty work. I traded it in after a few months and bought my daughter a Honda Civic. She drove that for 5 years and never had a problem with it.
            The KIA dealer did do the repairs, but a car or gun or optic is lifetime, it doesn’t mean much when you are wasting a day or more every time you turn around.

          • Lt_Scrounge

            I worked for the third largest Honda dealership west of the Mississippi river when I first got to Phoenix in 1999. Nice cars, but I wouldn’t buy one of their Pilots or Ridgelines. They are both built on a unibody from the Odyssey minivan. In other words, they look like SUVs and Trucks and will work fine for those who aren’t going to venture off the pavement, but that’s not what I’m going to use a 4×4 for. I may not be on dirt much, but I don’t like getting stuck either. I’d opt for a Nissan or Toyota. The Vibe I have has a Corolla chassis and drive train with a few performance tweeks and four wheel independent strut suspension. The nice thing about Nissan and Toyota trucks is that they are actually made in America versus Chrysler and soon to be Ford. I won’t buy a vehicle from the UAW owned Chrysler or GM.

      • SirOliverHumperdink

        Have you seen Eric trying to destroy the pistol? Hammering bolts into the barrel?

        • Kivaari

          No. I just don’t care for such guns. I would be embarrassed to be found with one. Nothing stops them from making a gun pleasant to the eye. They seem to go to great extremes to make their products ugly. Add the fact that many of them are unreliable, there is just no need to have one. People say they make a good “truck gun”. I wouldn’t want a thief to steal any gun, so I lock them up and use nice S&Ws or Glocks.

      • ChierDuChien

        It’s the steel that’s melting, not the pot metal.

        • Kivaari

          Not on the Hi Points. Zinc guns will fail in the zinc parts before the steel parts melt.

  • Jing

    This problem is easily solvable.

  • Blake

    So, this is what you meant by “heat flux”? 🙂

  • Blake

    So now he needs to test a roller-locked action for comparison. PTR-32 would be appropriate as it’s 7.62×39 like the AK they tested…

  • That FW episode is hilarious. “You know how hot the barrel is. You know. So hot that I can hold the railed handguard with my bare hands.”

    • Twilight sparkle

      Lol that’s true, but it still didn’t beat the time that the ak47 was supposedly chambered for 7.62×51 instead of 7.62×39, and they weren’t talking about a saiga.

      • Kivaari

        The script writers for that show were obviously not gun people. Having an editor that knows about guns would have stopped the many errors that hit the TV. It had to be embarrassing for the host of the show to make so many simple mistakes. OR, was the host a serious person or just someone that had friends in the video business? I’d want to have every episode having those dumb mistakes re-edited or never shown again. These kinds of mistakes make it to TV, AND into what should be serious reference books. The errors found in what should be high quality books (especially British ones) can fill a book. It seems that no one in the publishing business has real experience with guns.

        • Twilight sparkle

          Unfortunately there probably where people who called themselves gun people there, but I’ve seen people who thought they were gun people who couldn’t tell the difference between a glock and an XD.

          I’ve found that Janes didn’t have too many errors, shooters bible and gun traders guid however sometimes feels like it’s nothing but errors.

        • Joshua

          My favorite part of the 416 video is where he brags that it can be shot upside down……like really! Omgz guys it fires upside down!

  • Uniform223

    you have to hand it to H&K’s marketing… they really know how to play up stuff even if its incredibly marginal. I never put much stock in piston systems ARs because I’ve never seen/read/heard any REAL benefit after doing my own individual research. The Iraqvet8888 video pretty much proves everything I believe.

    • Twilight sparkle

      The only way it kinda makes sense is in the m27, that’s the type of gun where you might have lots of rounds down range before you could clean it and the piston does run cleaner. For civilians DI is king no matter what role the rifle is in.

      • Uniform223

        “that’s the type of gun where you might have lots of rounds down range before you could clean it and the piston does run cleaner”

        keeping a gun clean doesn’t have much of a real operational effect of a rifle/carbine for combat. Really all you have to make sure is that that rifle/carbine is lubricated. This goes for both DI and Piston systems. Cleaning (if anything) just slightly increases reliability over its service life. You still have to clean your Piston driven system. The only difference is that you’re cleaning a different part of the weapon. So even with the M27 I don’t see any real operational benefit over M4A1s.

        • CommonSense23

          I don’t think people have any idea actually how much a pain it is to actually clean a HK416 versus a M4.

          • Twilight sparkle

            I would imagine you get rock solid carbon on the piston head like what happens to an ak.
            I’ve never disassembled one but I figured it broke down like an sks where the piston and has tube come off easily or am I wrong?

        • Twilight sparkle

          Most of the moving parts except the gas system of the piston system would have less carbon build up to gum up the gun.
          After hundreds of rounds your oil is probably cooking off of wherever you put it so it’s not going to do much good anymore so I kinda figured it would be a good idea to keep as much of the carbon out of as many moving parts as possible

          • Uniform223

            The only benefit I’ve seen and experienced with piston systems is that they can go longer without lubrication. Even then most soldiers/marines don’t carry enough ammo on their person to make that system dry. Its just good practice to keep your weapon lubricated regardless if its DI or Piston.

      • CommonSense23

        Why do people think the a op rod driven AR needs less cleaning than a DI one?

        • Twilight sparkle

          I would imagine you probably don’t have as much carbon built up on the bcg.

          • Most of the carbon fouling can be wiped off by hand, so it doesn’t much matter how much there is. The only places I’ve ever seen carbon fouling build up in the hard, difficult to clean way that many people describe are on the bolt stem in the expansion chamber, and in the flash hider, both non-critical areas. You wouldn’t clean the inside of the flash hider even for a white-glove test, and cleaning the bolt stem is unnecessary for functioning.

            Having said all that, sure, piston guns run a bit cleaner, but unless it’s a really good one that costs twice as much or more what a bog standard DI gun costs, they also don’t work as well.

  • Sianmink

    28 magazines as fast as you can load and fire them.

    It’s safe to say that none of us will run into a situation where that is necessary, but I wonder at what point the damage started.

  • Kivaari

    Is there an actual reason to want a piston driven M4? Seriously, what is wrong with the DI guns? Over the last 50 years when witnessing an M16A1 or AR15 rifle fail, it has been the result of faulty ammunition OR the use of very poor quality parts.

    • tts

      No good reason to want one. They exist solely because producers are looking for a gimmick to push sales at higher price points since everyone and their brother is now making DI AR15’s and mix master M4’geries which knocked prices down since supply is through the roof.

      So they pushed the “PISTONS WOOOOO AK HK LIKE RELIABILITY BETTER THAN THAT DI SHI444T CLEAR EVERY MUTHAPHKKER IN DA ROOM” hype and just enough people bought into it that its still around.

      As far as guns go piston conversion AR15’s aren’t exactly terrible guns now, though some kits were really bad at first, but they aren’t any better than DI AR15’s and have some downsides (significant increase in forearm weight makes them surprisingly lousy to handle + higher cost + worse parts availability) that make them pointless when all things are considered.

      • Kivaari

        That’s pretty much what I have thought about them. There really is no serious need for piston driven ARs. Our country would have moved to piston guns if they actually provided a benefit to the game. I have noticed that a couple of the big piston gun makers are now pushing the DI guns. A bit funny considering how hard the piston guns were being pushed. I’ve lost count of how many ARs I had. They all worked well when fed good ammo.

        • tts

          Yup. I hope piston AR15’s go away entirely. Better to see the development dollars and efforts by companies spent on something actually better instead of a half assed retread of a existing weapon.

        • Lt_Scrounge

          I would say that if the Special Forces went to piston upper HK 416s over the DI M4s, they probably had a good reason. I would think that the DI vs Piston argument probably has more to do with the quality of the two weapons. A PoS is a PoS whether it is DI or Piston driven. I’ve inspected enough dirty M16A1s as an arms room officer to prefer the piston driven variety myself. Since you would be hard pressed to find a decent DI model for what I paid for my flat top piston model, I couldn’t see any reason to deal with the dirt in the upper receiver. If I’m going to be in a serious firefight, I’ll probably grab my AK anyway.

          • Kivaari

            We have seen SOF types test different guns over the years. I suspect you will see most of them packing DI guns. Trying other designs in the field has not led to adoption of piston guns. If you look around at what guns are being purchased you’ll notice most are conventional DI variants. In a few articles on TFB I remember seeing the 1911 type pistols are being withdrawn from service and Glock 19s are filling the void. We have observed limited use of piston carbines and troops going back to the M4s. From reading many articles it appears the SOF-types find the M4 to be the best.

          • Lt_Scrounge

            From what I have read, the HK416 was so popular among the Green Berets that other units were asking for it and the powers that be didn’t want to spend the money to refit those units so they ordered that the HK 416 be withdrawn from the field and the SF guys were issued a type of M4 that only had 3 round burst capability versus the one they had before that had both 3 round and full auto. They eventually got their full auto ones back.

          • Kivaari

            I don’t know why anyone worries about this issue. I don’t expect warriors to fire so many rounds in such a compressed time frame. Rifles just don’t get fired like that in the real world. A fighter wont be packing 800 rounds on his person. There will be breaks in the battle where there are simply no targets to shoot at. A fighter will likely be moving about his area, and will have highs and lows matching the actions of enemy forces. A trained warrior knows that just blasting away at the enemy on full auto is a waste of ammunition
            These “tests” are for entertainment purposes, and not a serious experiment.
            From what I have read, the moving parts induce accuracy defeating problems. Extra bits and pieces moving about causes a reduction in accuracy compared to DI guns. I’ve only taken a couple piston guns apart. In one of them it took some added time to reassemble the little parts. Parts that were small enough to get lost, especially in the bush. The FAL is a fine rifle. Since a fighter couldn’t carry enough 7.62 NATO ammunition to reach a melt down it’s a mute point.
            I believe you are referring to the Wanat (spelling?) incident. It doesn’t appear to me that the M4s failed. I’ll go back and read the article in TFB.

          • Lt_Scrounge

            I have to agree with you about hoping that this is a moot point. From what I read, (not from official CYA reports) there were numerous weapons that simply failed to function due to the internals seizing up from the heat that included both M4s and the M249s.

            The incident I am talking about is where they stuck a combat outpost on a ledge overlooking a town where they could see into the town but also had high ground behind them that they didn’t control. Not a smart location to build a base unless you control that high ground. They were drawing down the base and had under 50 soldiers there, which the locals KNEW. Under the ROE, they could watch hundreds of armed hostiles go into a mosque but weren’t allowed to do anything until they began charge up the hill firing AK, RPGs and RPK machine guns. I’m pretty sure that one Staff Sergeant got a CMH for his actions that day, though I think it was awarded posthumously.

          • Joshua

            What? SF never had the HK416. SF were the first to say the Block II M4A1 was mechanically superior to the Hk416. Also the only way SF was carry around AKs was because they were training and imbeded with indiginious forces.

            The unit you mention is AWG and they got the HK416 because the general issue M4 was lacking.

            They use the Block II M4A1s now and have no complaints about them.

            You are also incorrect on Keating. Keating was Kamdesh, there were no reported failures of any rifle during that battle and multiple soldiers reported expending 40+ magazines through their M4 over the duration of that fight, yet no one had any stoppages of any kind.

            You are thinking of Wanat, where practically every rifle failed in some form. However only 2 M4’s failed from an actual error. One M4 was shot from a 7.62 and killed the owner of it, and the second was discarded when it got to hot to hold barehanded.

            I’m not sure where your getting your information, but its practically all wrong.

          • Uniform223

            That tired argument…

            “Oh well special forces uses the HK416 so it must be the bees knees… ”

            Guess what. The primary weapon for US Special Forces is STILL the M4A1.

            ” A PoS is a PoS whether it is DI or Piston driven”

            I agree

            “I’ve inspected enough dirty M16A1s as an arms room officer to prefer the piston driven variety myself. Since you would be hard pressed to find a decent DI model for what I paid for my flat top piston model, I couldn’t see any reason to deal with the dirt in the upper receiver.”

            so now your argument falls on personal opinion. That is alright but you’re personal opinion and experience shifts into bias. The only REAL difference in cleaning a DI and Piston is WHERE you clean it. Ever clean the piston head or the gas block? If carbon build up is such an enemy of fire arms then the gas block and piston needs to be cleaned too… but you don’t here the piston fan boys say that do you?

            Also you’d have more of a chance finding a high quality DI build that runs just as good as a more expensive Piston build. If you’re paying for DI build that costs just as much as a Piston build chances are, you’re paying for the brand name at that point.

            “I couldn’t see any reason to deal with the dirt in the upper receiver.”

            I’ve ran my M16A2 and later M4 dirty all the time when I was in and my rifle/carbine never gave me a problem.

            http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/

            “If I’m going to be in a serious firefight, I’ll probably grab my AK anyway”

            AKs are good but I’ll go with what I am more familiar with…

          • Kivaari

            An issue with all kinds of guns, is people just will not clean them regardless of what kind of action is involved. Single shot muzzle loading rifles often are found with last years load still in place. Like Remington M700s, where every external surface is nicely cared for, but the inside of the bolt holds rusting parts. People simply wont do basic cleaning. At least in the military some one can tell the soldier or sailor to go back and clean the damn thing. I had them try to hand in loaded rifles, and they say they cleaned them.

          • Joshua

            Yeah because they didn’t feel like waiting for the Mk18 to mature and the HK416 has a very slight advantage when run full auto, suppressed, and with a 10″ barrel.

            The difference is very minute, but the 416 does get about 1,500k extra barrel and bolt life over a CQBR run in an identical manner, and to black side that difference is worth it.

            Just a FYI black side us M4A1 uppers mounted on 416 lowers when they need want a 14.5″ barrel. At that barrel length the M4A1 and 416 perform for all intents and purposes identically, and the M4A1 upper is much lighter, cheaper, and easier to maintain.

          • Kivaari

            I like AKs, having owned around 25 variants starting in ~1976. I don’t own any now. The biggest reason are the poor sights. Great rifles for young eyes. Today, there are many good scopes and sights that simply were not available 15 years ago. I love ARs, as I can do any kind of work they may need. Because I always go deep, by having piles of magazines, ammo and repair parts (needed or not). I’ve just settled on ARs, Glocks and S&W revolvers. Since I am in my declining years I just buy good stuff an no longer have that sense of “need” getting me to buy another pile of gear.

          • Lt_Scrounge

            My eyesight was so bad when I was younger that I could never get used to the sights on an M16a1. I was raised on the AK style sights so I was used to them. As presbyopia set in, my eyesight actually got much better. My shooting glasses have half the correction in my right eye as my regular glasses. They allow me to see the sights clearly with my right eye and the target clearly with my left one. Then my brain just superimposes the images over each other. Instant depth of field.

      • Nocternus

        I would say the strongest advantage of a piston gun is when i clean it after a trip to the range. after 500+ rounds I clean my BCG with a Qutip. As for your significant weight increase to the forearm. I suppose you consider 2 ounces considerable. At least that is what you have been telling your wife all these years.

        • Kivaari

          I clean most of my guns in hot soapy water. It doesn’t add much time to the job. I don’t have a tube like on an AK or FAL to worry about.

          • Xanderbach

            My AK has said tube, and I run a bore cleaner down it every 1K rounds or so. Admittedly, I don’t beat the hell out of it (or can afford much rapid fire) but the gas tube has never been a problem.

          • Kivaari

            Back a few decades when corrosive ammo inn 7.62x39mm was more common, I found that shooting the rifle and not cleaning it right away gave rust a real head start. Just overnight in the bush would allow rust to grow dramatically. Much of it was not the gun parts rusting but steel deposits from the ammunition.

          • Kivaari

            It is less of a problem for todays shooters. In the 60-70s,ts of corrosive 7.62mm ammo was available. I would have considerable growth in the gas tube. In non-chrome lined bores and pistons. Like the Valmet 62S. It paid to clean it ASAP.

        • tts

          If it was hard to clean a AR15 that would be a big advantage but its not so I don’t see a point there at all really.

          Its great if your piston AR15 only weighs 2oz more than a DI AR15 but ones I’ve picked up added closer to a half a pound to the weapon and put it out front of the weapon under the forearm.

          Adding any weight at all near the front of the gun is going to make it feel lots heavier than it really is. A good historical example of this would be the M1903 vs M1917. Many people hated the M1917 and often mistakenly thought it weighed 11-12lbs despite only being 8oz heavier due to its front loaded weight.

          Weight distribution and weapon balance is a known problem and your attempt to downplay it while insulting me smacks of pure emotion. What is going there? Do you feel insulted because I’m poo poo’ing something you paid good money for?

          Its just a product and it doesn’t care about you man. Liking guns is fine, getting mad at others over them isn’t.

          • Nocternus

            Who is mad? I have both DI and piston AR’s. One I scrape carbon off the bcg the other i clean with a qutip. If you can’t take a joke i realize my statement may have hit too close to home. All kidding about your small penis aside though please continue with your Piston hate.

          • Joshua

            You know you don’t have to scrape anything right?

            If your spending more than 5-10 minutes cleaning your gun your doing it wrong

          • ostiariusalpha

            I had to scrape the tappet on my FS2000, but that was my fault for not cleaning it after 1000 rounds.
            ¯_(ツ)_/¯

          • Uniform223

            only time I had to do that was making it spotless before I turned it back in to the armory. I found it ran just fine so long as I used a rag to wipe the BCG and receiver then run a bore snake through the barrel about 3 times.

          • Joshua

            Ahh yes the white glove cleaning regimine.

            That’s left over from days of corrosive primers, it’s amazing how institutional knowledge(incorrect) hangs around.

            Honestly it would better to wipe down the whole rifle, and then relubed it before turning it in….they won’t do that though because oil is icky and Scarry.

          • Lt_Scrounge

            Tell that to the soldiers who couldn’t get their M16A1s clean in under 4 hours. Mine was done in under 20 minutes, but I was bringing my own cleaning gear not using the issue stuff.

          • Joshua

            Yeah, but that’s not needed for the actual function of the rifle. It’s leftover from the days of corrosive primers.

          • Lt_Scrounge

            Are you aware that the Army began mandating non corrosive primers during WWII with the introduction of the M1 Carbine? The 30 Carbine round was the first round to actually require non corrosive primers in the specifications. I can guarantee that we were not using corrosive primer ammo in the mid 80s. They may have had the wrong kind of powder, which was the problem when they fielded the M16s in the 60s, but they were not issuing ammo with corrosive primers. Primers impact the barrel, not the interior of the receivers. These things had carbon caked and baked onto the bolt behind the gas rings that had to be either scraped off with a knife or with a bronze brush. That’s not from corrosive primers. That’s from gas being blown back into the receiver. They even make a tool specifically designed to scrape carbon out of and off of the bolts.

            I’ve inspected M16s hundreds of times. You can think what you want, but I know what I have seen. I don’t consider blowing 500+ degree carbon back into the aluminum receiver a means by which to insure a clean, fully operational weapon. The aluminum may dissipate the heat better than steel, but it also warps and melts at a much lower temperature as well. Heat is bad for a firearm. It weakens both internal parts and springs. You want to keep your receiver as cool as possible. Unless you like swapping out springs which lose their temper when heated and cooled excessively.

            Anyway it’s all subjective. I’m hoping that none of us will ever have to determine which is better by firing the number of rounds that it takes to induce a failure in a civilian context. Honestly, history shows that I am hoping in vain because political forces in DC are pushing us ever closer to the brink of an armed revolt, but I can still hope it doesn’t happen. Once I get started at my second job and get some of my debt paid down, I will probably part with the money for a paratrooper model FAL and use it for my weapon of choice and keep the ARs and AKs as backups.

          • Uniform223

            SSG Wilson – If I run this cu-tip over that bolt and in the star chamber and it comes back black… its not clean

            Me – Hooah Sgt!

            8 years later with my own (used) Colt 6920 after running a carbine course.

            Instructor – Why are you spending all that time trying to clean the star chamber?

            Me – cause I need it to be clean

            Instructor – trust me it doesn’t. Just make sure your system is wet.

            2 days later with no cleaning

            Instructor – no cleaning today?

            Me – nah… just wiping the BCG and running a bore snake.

            Instructor – Still works huh?

            Me – yup!

          • Lt_Scrounge

            Yeah, but you didn’t have a Captain with a BG for a father, an MG for a father in law, and a full bird for a brother who told you that you would be held accountable for any rifle that he found in the arms room that wasn’t spotless. I did. It took about 6 field exercises of us being there until 3 am before he decided to see what the hold up was. I looked him dead in the eye and said Sir you told me it was MY ass if you found a dirty rifle in this arms room, so I’m not accepting anything that isn’t spotlessly clean. I’d be more than happy to allow the Platoon Sergeants to vouch for the cleanliness of their platoon’s weapons, but if I’m going to be held responsible than they’ll be spotless and we’ll be here until they are. At that he decreed that all weapons were to be inspected by the platoon sergeants and they would be held to account if he or I found one dirty the next day. End of the late nights inspecting weapons.

            I ran a four day defensive handgun course at Front Sight with a Tristar C-100 CZ-75 knock off without cleaning or lubing it. 600+ rounds over four days and not a single malfunction of any sort. I had my full sized CZ-75 in the car in case something did break but it wasn’t needed. I got that Tristar for $259 at a pawn shop with two magazines and in the original box. I used the Tristar because the stainless CZ is one heavy pistol.

          • Uniform223
        • MichaelZWilliamson

          If the gas tube fails on your AR, you have a bolt action rifle.

          If the piston fails, you have a club.

          • Nocternus

            How is that exactly? If my piston fails it will still operate as a bolt action also. I can turn the gas system off and run it like a bolt gun now if i wanted.

          • MichaelZWilliamson

            Did you see how hard he was yanking the charging handle to cycle it?

            Bent op rods stop guns dead.

          • Uniform223

            ever see someone have to “mortar” an AK or other piston driven systems?

          • cageordie

            It’s no different. You can still cycle it by hand, which he was.

          • MichaelZWilliamson

            He was having to beat on it. Failed gas tube on an AR makes it a straight pull single shot.

            Clearly, you’ve never had to kick start an AK, so this discussion is pointless.

            And you’re wrong.

  • Slobberjaw

    Great video! Keep em coming!

  • Roland

    How much cleaner was the piston bolt compared to the DI bolt?

    • Kivaari

      The piston guns have more surfaces that need to be cleaned. You need to clean the piston, then the tube it runs in as well as any cap piece (like the FAL). Cleaning an AK takes more time thanks to all the hardware riding above the barrel. If you can’t take a few minutes to clean an AR bolt assembly, just why do you have one?

  • 7n6

    Mushroomed carrier definitely not confidence inspiring. Does the gun have multiple gas settings?

  • Uncle Festet

    Someday, someone is going to become Rich when the invent a better wat to dissipate that heat.

  • Kelly Jackson

    Back when Discovery showed real shows there was an episode with the HK 416 firing multiple mag dumps and then the shooter removing the bolt carrier and it was cool enough to touch.

    I never really understood what these goofy “torture” videos prove other than some people just have more money that sense.

    • Put all thought of Future Weapons being anything but essentially paid advertising with documentary window dressing out of your mind.

    • Joshua

      You can do that with a basic M4.

  • Kivaari

    The peening on the BCG was, most likely, not a result of heat. That’s my GUESS. So regardless of having heated parts or not, it would seem that the BCG damage would have happened if the rifle was shot one magazine per DAY. Was the parts failure due to inadequate materials or design? Again, my guess is it is an inferior design and would have failed after such limited use. And 800-900 rounds is not many cycles for a rifle.

    • If it was not caused by heat, it would have to be a manufacturing defect of some kind. If properly heat treated, the parts shouldn’t do that.

      • Kivaari

        I would think this design is a failure. If it were machined from one piece and not screwed on, having proper heat treating (of an adequate metal alloy) it may work OK. As this shows, the quality of this part is inadequate. Having the impact forces hit this spot puts “un-natural” forces onto a part never designed to take repeated hits. A DI BCG runs very genteelly compared to these guns. Perhaps if people want a piston rifle, they should buy one that was intended to run that way. These after-thought piston alterations just don’t make sense.

  • Doing torture test are fine but I have to get the companies permission to possibly mess up their rifle, handgun or whatever.

  • Twilight sparkle

    I can agree with that, but it’s the only video I could think of that had anything to do with the heat transferred to a piston driven AR bcg. I remember a vague thing from h&k a long time ago but I probably couldn’t find it very fast.

  • stephen

    I never really understood destroying a rig in this manner. Why? For 99.99% of people they won’t come anywhere close to these temps. I guess it makes for subscribers and views though.

    I spent a career in the Army and never had any issues with any M16 variants = gas pistons work great. With that said I have a piston Ruger SR556 and have about 8K rounds with no problems (much cleaner than gas piston).

    Oh well, I remember a time when destroy a firearm was considered stupid – guess I’m just old fashioned.

    • ostiariusalpha

      While it is generally known that one should either entirely ignore marketing claims or take them with a large dose of salt, they can worm their way in to people’s beliefs and influence unconscious predispositions. A public video like this, where a gun is pushed to its limits, can help dispel that unconscious mythology that even otherwise sensible people can pick up. There are obviously military tests that have already covered these matters in a far more rigorous manner, but YouTube is much more accessible for the layperson.

  • Kirk Sides

    What about doing a failure test utilizing the Adcor upper receiver? Their bolt carrier has the piston already on it, not separate.

  • Paul W.

    might need a roll cage to prevent windscreen from popping out! body flex.

  • Military Arms Channel

    A bit more info on the VEPR. We took the rifle back to Definitive Arms. We gauged the rifle and the headspace was still spot on. After it cooled and we cleaned the copper fouling from the gas block (a lot of it has accumulated for some reason) and the gun returned to 100% operation. The barrel did droop so the point of impact is low by several feet at 100 yards, but the gun still works. I’ll do a video with it in the future.

  • guest

    Though piston AR upper is probably a good idea, it kinda still steps on its own d**k so to speak because the system was never intended to run with a piston OS.
    That spot on the bolt that took a beating is the witness to the problem: if a piston and rod are independent from the bolt that means ANY gap between the two will during firing cycle accelerate the oprod to a higher speed, then it will impact the carrier and only then will they both travel at a slower speed which will be the bolt velocity that is within acceptable/needed speed.
    AK does not have that problem because the oprod is fused to the carrier as a single piece, hence no difference in velocity and no impact from the oprod.

    Plus the fact that from the very beginning what is usually a pretty solid system in terms of “slap the mag in and forget about it) was already failing. So it’s a problem with the lower too.

    All this s*** goes back to a very simple reason: AR platform has too many parts, and is unnecessarily complicated.

    • Uniform223

      “AR platform has too many parts, and is unnecessarily complicated.”

  • Mike11C

    I had my own great debate on piston vs DI a while back. In fact, I’ve been mulling it over and over since the early 80’s when the “Rhino System” first came out. In this imperfect world, it came down to parts availability and inter-changeability. With a DI gun, when some part fails, any gun shop will most likely have a replacement but, if a part of a piston gun fails, they’re all proprietary and, you have to get the part from the manufacturer or one of there dealers. That could take weeks or even longer. There are pros and cons to each system but, for me, it’s all about the ability to keep it running with the least amount of down time. That means it’s DI for me.

  • Eric B.

    The real problem here was the CONVERSION of “a formerly direct impingement design”. This is one of those the worst of both worlds situations.
    Test instead, the LWCI AR or other high quality piston AR that was designed FROM THE START as a piston gun snd see the difference in durability compared to, say, the new LWCI DI gun. I’ll take a piston gun any day.
    A Steyr AUG full auto is a short stroke piston rifle that will, I am very sure, withstand many more torture rounds than the converted AR just demonstrated.
    Of course, as stated below, ALL testing needs to be done with identical barrels, or at least as identical as possible between different manufacturers. Apples-to-apples, ya know.

    • Erm, the LWRC is also a conversion from a formerly DI design.

      You know, when writing this article, I had wondered if the piston fans would come out of the woodwork and start claiming that LMT is not a good manufacturer. I shouldn’t even have wondered.

    • ChierDuChien

      The AK variant subjected to the same sort of testing failed at about the same round count. Abusing your weapon, regardless of what system or manufacturer, WILL break it.

  • Slobberjaw

    Love these videos! It’s great to see for real what everybody speculates.
    “Mine’s better than yours cuz…”
    “Nuh uh! Mine’s better cuz …”

  • Joshua

    There’s a reason SOCOM pushed for the development of a heavy barrel on the M4A1.

    And as I mentioned earlier it takes around 870-911 rounds to kill a gas tube.

    • Uniform223

      and you need to run it HARD… ridiculously hard that no real world situation would never need it to be.

      • Joshua

        Well yeah. SOCOM decided they needed a heavy barrel because lab testing fire to destruction showed the M4 barrel failed before the gas tube.

        It wasn’t a real world need

        • Uniform223

          The only real world benefit I would see from a heavier barrel is that it make the rifle/carbine (slightly) more accurate because there would be less barrel whip and it would better handle heat. Here is something most people don’t think about. Thicker barrels handle heat “better” but… they keep that heat longer because essentially the thicker the barrel the more insulation for the heat to stay in the material (metal).

  • Ed Foster

    I was testing a piston gun up at Smith & Wesson several years ago, and had a catastrophic failure at a very low round count. I imagine I still have the test results around somewhere if anybody’s interested.

  • Joshua

    That’s not true….not at all.

  • CavScout

    Those LMT’s are about as it gets for testing. I really don’t think an Anderson or many others would have lasted nearly as long. As for the LMT piston gun… it’s like a SCAR or ACR; except you can actually switch out barrels and calibers, and quickly and rather cheaply. So you get the amazing quality AND the features you were supposed to have with the video game guns. But then I’d still rather have the DI guns for all except probably the shortest barrels.