Heckler & Koch HK416 internals video

This video shows the internals of the H&K HK416. One nifty feature is that the handguard screws were designed so that they could be unscrewed using the bolt lugs. The video is well worth watching.

Video was made by GunWebsites.

The civilian HK416 is expected to arrive next year.

[ Many thanks to the reader who emailed me the video. ]

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Josh

    That was a decent video to show and explain the HK weapon. I had to laugh when he said “they wanted to make this a field expedient weapon.” Let’s find that guy a dictionary. Other than that, I thought it was informative and gave a decent overall explanation of the system. (I guess it helps if you’ve spent years disassembling and cleaning an M4 and can see the fundamental design difference in a weapon that looks nearly identical from the outside.)

  • rusgunnut1

    forgive me if i’m wrong, but isn’t that a 6.8mm magazine?

  • rusgunnut1

    Forgive me if i’m wrong, but that magazine looks rather short, I thought that that style of mag was for 6.8? Either way, I love anything that has that sort of dual function.

  • Lance

    A sweet weapon, I can see how the Army wants a piston M-4 like it.

    I dont see the French dumping the FAMAS for it though.

  • jdun1911

    Does the guy work for HK? He seems like it.

    HK wasn’t the first one to do a piston AR. I believe that honor goes to Colt back in the early 70’s.

    Any weapon that have water on the barrel and fire without draining will go KB! including the 416. HK can’t defied the law of physic.

    It’s a shame that he doesn’t show or tell how HK deals with the carrier tilt. The carrier tilt sooner or later will destroy the buffer tube and the upper receiver.

  • Stella


    People have put many thousands of rounds through LWRC piston based rifles and not encountered problems with carrier tilt. If I remember correctly an LWRC rep said they have had very few rifles (less than ten) exhibit tilt and all were prior to a carrier design upgrade in 2008.

    Assuming HK has done solid engineering I doubt that tilt will be a major issue.

    • Can someone please explain “tilt” to me. My understanding, quite possibly wrong, is that it is the tilt cause by the piston pushing against the carrier causing it to tilt upwards and scrape against the receiver.

  • Stella

    I’ll do my best:

    The carrier key of a GP AR is solid or a raised integral plane to provide something for the piston to strike and thus cycle the action. The piston strikes the key off axis introducing the risk that the BCG will recoil back into the buffer tube too low; the AR, unlike most piston native designs, does not have rails to keep the BCG on track. This can shred a lower and buffer tube.

    Piston AR bolt carriers are designed to compensate for the off center impulse produced by the piston. In the case of LWRC, from what I have read and seen with my own rifle, they have done quite well.

  • Lurpy

    Posted by jdun1911on 24 Dec 2009 at 8:47
    “Any weapon that have water on the barrel and fire without draining will go KB! including the 416. HK can’t defied the law of physic.”


    Unmodified factory models.

  • Gutao


    why they dont put some rails on it? ( LOL,the ACR have rails ^^)

  • jdun1911

    In a DI action, the recycle gas is use as an op-rod. The gas enter from BEHIND THE BOLT into the cylinder. What happen when gas enter an open space? It expand in all direction to fill up the space. In this case it push the bolt forward to unlock it. At same it start to push the bolt carrier backward. This balance it out thus it doesn’t need a rail to hold the bolt carrier.

    In a piston AR the metal op-rod hit the carrier key. This cause an imbalance, by pushing the carrier downward with no means to counteract it. So what you have is the bolt carrier grinding (destroying) the extension tube and receiver.

    The standard AR15 DI has a piston it just doesn’t have a physical op-rod. It relies on the recycle for it.

    All parts should be lube it silly not to.

    It should be noted that the HK guy on the video stressed that the piston should be lube. What happen when the piston binds? In a AK you slam the charging handle into an unmovable object. This should take care of the malfunction because the piston is attached to the carrier handle.

    In an AR the charging handle isn’t attached to the piston. If the piston jammed, you have two option. Collapse the stock and hit it on the ground as fast as possible. If that don’t work you have to do a complete dissemble. At best your piston AR will become a single shot bolt action rifle. At worst it will not work at all.

    You give up a lot of advantage for some perceive improve reliability.

  • Stella

    It would be rails “in” it: putting rails inside the upper receiver and then redesigning the BCG for it would likely effect lower compatibility, the Raison d’être of the gas piston AR upper.


    I think you minimize the very real problems of direct impingement and yet make into mountains hypothetical issues with short stroke gas pistons.

    There are many short stroke piston rifle designs. Most do not have failures related to the piston jamming due to the force being applied when a round goes off and the fact they only need to travel an extremely short distance. Yes the HK 416 had cold weather problems; however this was largely attributed to the use of “green” ammo and was also during a nascent period of development. It’s important to note that among the M-16s many, many “teething” issues was cold weather failures related to ammo.

    At worst you are exchanging a very rare problem that removes very common failures. The much dreaded carrier tilt is incarnate a few metal shavings and dings in the buffer tube if it materializes at all. The flaws of DI, however, are plain to see and even the army is going to dump it now. DI heats the internals of a rifle until resplendent, undermining components and boiling away lubrication. It also introduces fouling to the most important areas of a firearm.

    I don’t think gas piston uppers and certainly not retrofit kits are the long term solution for America’s next combat rife, though I could be wrong. To say, however, they fix fewer problems than they create seems equivocal if not myopic: I mean, nothing bad has ever happened to a gas tube in combat, right?

  • whatever

    One thing I don’t like about the HK design is the need to remove the forward hand-guard in order to access the gas piston.

    On the AR upper receiver it looks like it wouldn’t be too hard to have a steel insert around the rear pin in order to counter bolt tilt.

  • Brad

    The M-16 DI gas system was designed to function with a 20 inch barrel at 700-900 RPM cyclic ROF. What’s the cyclic ROF with a shorter 10.5 inch barrel? Over 1000 RPM? That kind of excessive pressure and carrier group velocity is what will chew up and wear out an AR prematurely, degrading reliability. If nothing else a short stroke op rod system can be designed to moderate the cyclic rate down to a tolerable level.

  • Gutao

    If the actual AR design doesn’t do what it needs to do,why they simply dont make a new one? One that keeps the things they like and change others they dont like? Thats why,i think the ACR is so neat (at least if the hype is correct),multi caliber piston gun,reliable,abidextrous and modular,what else do you want?

  • jdun1911


    AR15 DI receivers in theory will last forever at whatever barrel length is used. That means countless of rounds through it. With that said changing barrels over and over again will sooner or later strip the receiver barrel threads thus making the upper receiver useless. It might happen in 2 barrel change (because of over torque or lack of grease on the threads) or 1000 barrel change.

    The lower however will last forever.

    SBR will have high cycle rate. They are very harsh on suppressors. AR15 with short barrel can be unreliable because the extractor isn’t strong enough to pull the spent case out. The fix is to upgrade with a stronger spring/O-ring for it. Heavy BCG and buffer is another way to slow down the cycle rate.

    AR15 extractor upgrade kit if any of you are interest in it.

  • Crawdad

    ” The piston rings are about the only thing that need to be lubricated, other than that, the whole system can run dry.”

    I think the last time someone said that about a rifle meant to be issued to troops, we ended up trying to find a way to replace that system.

  • A round of applause for your blog.Really thank you! Really Cool.