H&K G41: The HK33 Meets the M16

The H&K G41 was developed for the NATO trials of the early 1980s, which were set up to look at both rifles and cartridges for NATO standardization (although they did not end up choosing a rifle). The gun is a basically an HK33 roller-delayed system set up to use standard M16 magazines and with a selection of other M16 features like a dust cover, forward assist, catty handle, and bolt holdopen/release. Two versions were made, a standard length rifle and a shorter barreled carbine with a collapsing stock. The system was not a commercial success; most potential clients opted to either buy the HK33 or the M16, rather than this sort-of hybrid.

It is worth noting that the G41 was the first H&K rifle to offer a 3-round limited burst option and the first to use the universal bullet icon selector markings, both of which have become commonplace on all their other weapons since. Thanks to H&K for giving me access to these rifles to bring to you!


    • The best way to get it right is to reread, revise, and then post. Before that, get a dictionary for difficult words…

  1. Ian, you forgot to show the G41 bolt head differing from the HK33 pattern. The extractor claw has been changed from the simple spring pushing down to a pivoting arrangement gripping around the bolthead. The bolt head looks more like the bolt head of an HK13 lMG.

    (repost to see why the posts do not get through anymore)

  2. Excellent show as always on FWs.
    If I understand it correctly, this was in fact the last roller locked HK rifle (part for commercial variations which followed).

  3. HK: Remember that time FN got everyone to agree on the FAL, but then the US decided to go with their own rifle instead? We won’t get caught like that, we’ve made it just like a US rifle, so they’ll have no excuse not to agree with it.
    USA: Hey, this is just like our rifle! Might as well keep the one we already have.

    Good try, HK, but going up against the US military procurement system? You never had a chance.

    • The G41 was for a) German Bundeswehr who didn’t get the “kraut-space-magic” wunderwaffe Geh-Elf caseless but still needed a rifle, preferably one with AR-type de facto Nato magazines, b) Maybe Sweden? I mean they are only a pro-Nato neutral, but they did use the G3 in the form of the AK4… Nah. They thought long and hard about the Galil before going with the FN FNC, c) Italy, which was looking for a replacement for the 7.62x51mm BM59, preferably a 5.56mm rifle that used AR de facto Nato magazines, and d) maybe Eire? Nah, they went for the Steyr AUG.
      e) Possible foreign sales.

      a) The G36 was a separate research track, and it used more polymer so cheaper and lighter.
      b) FN FNC as AK5.
      c) Beretta 5.56mm rifle. G41 too heavy.
      d) Steyr AUG.
      e) With tons of nations already building G3s, why would the G41 elicit a contract when it is too heavy for the caliber? No sales interest.

    • “Good try, HK, but going up against the US military procurement system? You never had a chance.”
      Well, some says that compromise is when both parties are dissatisfied and this seems to be example of it: not German enough or not American enough for customer.

      • There is no way in hell that the G41 would have ever been adopted by the US, and HK knew that going in. What would the point have been? Substitute a much heavier underdeveloped weapon for an already-issued one that was fully developed…? Yeah; just “No.”.

        The G41 offered nothing to anyone who already had a 5.56mm rifle, and didn’t even make much sense to anyone looking to buy one–That weight was the key thing, plus the recoil operation.

        • Yes. As it happened, some went to Turkey–A G3 user–and Italy, which as noted adopted the Beretta AR70/90.

          The Canadian M16 was adopted by the Netherlands and Denmark as well as Canada. Portugal still doesn’t have a standard 5.56mm rifle, although the elite and “snake eater” airborne types do have them, Israeli Galil, G36 like the Spaniards, and some SIGs. Spain went for the CETME-L and later the G36. France had some SIGs and G3s, but adopted the FAMAS. Turkey ultimately retained 7.62mm.

          Fast forward to the current moment and HK has done rather better by Nato:
          Tinkered and re-tinkered the L85.
          416 used by ultra-elite-special-forces-snake-eaters worldwide. Adopted by France as the “tip of the spear” as far as infantry armament goes.
          Norway too.

          Germany appears undecided about a Haenel design or still another Hochler und Keck produkt. At least it seems that die Ingenieure in Oberndorf a/d Neckar have any number of prototypes they can dust off, “breathe on” and repurpose to potential marekts.

  4. Why did HK abandon the roller delayed system ?

    Was it cost of manufacture ?

    It requires a too heavy bolt carrier mass to function ?

    It couldn’t be developed any further into something like the G36 ?

    The UK paid them £90 million to sort out the problems with the SA80, and that free R&D into the AR18 type locking system gifted them the G36 ?

    • Aren’t delay blowback systems a lot more ammunition sensitive compared to gas-operated (DI/piston) systems?

      The only place I’ve seen the G41 before is the old PC game Jagged Alliance 2. Certainly a bit of an oddball choice even in the late 90s.

  5. Why did HK abandon the roller delayed system ?

    Was it cost of manufacture ?

    It requires a too heavy bolt carrier mass to function in today’s lightweight weapons ?

    It couldn’t be developed any further into something like the G36 ?

    The UK paid them £90 million to sort out the problems with the SA80, and that free R&D into the AR18 type locking system gifted them the G36 ?

    • All cartridge powered repeating systems are sensitive to variations in ammunition.

      Unfortunately the blowback and delayed blowback systems tend to be among the more sensitive mechanisms.

      With short recoil (with a gas trap on the end of the barrel casing) and gas powered systems, it is possible to give a little bit more momentum to the bolt carrier than it actually needs, so it will still function with lower powered ammunition or cope with dirt and ice

      And design in a healthy free travel for the bolt carrier before unlocking begins, to allow even the highest pressure ammunition’s pressure to subside, before the locking surfaces are moved,
      Then to buffer the bolt carrier at the end of its rearward travel.

      You can also play tunes by increasing the upswept volume of the gas system, to give a slower impulse.

      These can be done at the design stage, and the gun shouldn’t require any drastic changes after that.

      For delayed blowback, there’s a smaller range of reliable operation
      On one encourage of that range is failure to cycle, at the other end are burst case heads and hot gas escaping, and sometimes even separated cases, with the front end of the case left stuck in the chamber.

      I gather that H&K had tens of different angles of wedges available on bolt carriers, to fine tune their guns to a client’s ammunition.

      But what happens on a joint operation?

      Actually, the picture isn’t very pretty for some gas operated guns either; I can’t remember which way round it was, but with British and American guns in Iraq and Afghanistan
      One wouldn’t cycle reliably with the other’s ammunition
      And the other way around, the extractors tore through the case rims. The pressures at the gas ports were different.

      • Gas-operated fire-arms might be equipped with gas regulator, allowing user to adjust it depending on ammunition and condition of guns. Was similar feature implemented in any delayed-blow-back fire-arm?

        • If the gas itself is used to perform the function of delay, like pushing a piston forward to offset the pressure on the bolt, then it is self-regulating because a stronger charge will lead to more delay. But then you have to keep that piston clean. And this does no good for roller-delay, which has been the most successful in the field. Has anyone heard of a gas-delay that doesn’t use some form of piston sliding in a cylinder?

      • I vaguely recall a discussion in the US to move to ammo that would provide better MV in their 14.5″ carbines, so if they existed, it doesn’t seem outlandish that a loading with much faster burning powder could cause problems for other guns.

  6. Ian mentions the barrels with different twist rates. 1 in 7 or 1 in 12 in relationship to bullet weight. Could someone explain the differences in barrel twist and how this affects ballistics? Thanks.

    • They were changing to from a 55 grain lead core bullet to a 62 gr one with a steel penetrator. Heavier = longer & lighter material = longer still. Shorter bullets require slower twists and longer bullets need fast twist rates. You’ll see most .223 rifles designed for varmint hunting using 45 – 55 gr bullets have 1/14 – 1/12 twist, while 5.56 msr’s will have have 1/9 – 1/7 twists for 62 – 77+ gr bullets.
      While lighter bullets usually shoot reasonably well through a fast twist barrel, long, heavy ones shoot terrible with a slow twist. A long bullet needs to be stabilized properly: think of a tall spinning top, when it’s spinning rapidly it stays upright & doesn’t move around. When it slows down, it wobbles & wanders.
      Not having a phd in physics, this is the best I can do. Hope it helps!

    • Assuming that your bullets have approximately the same nose and tail shapes.

      A heavier bullet in the same calibre, will be longer.

      The aerodynamic pressure on a bullet, is normally in front of the centre of gravity.

      That means that the bullet is constantly trying to tumble.

      Spinning the bullet results in it stabilising like a gyroscope, and travelling point first.

      It is important that the bullet is not under stabilised (it would tumble end over end)

      Or over stabilised, which would result in it keeping the nose up attitude that it was fired in, through outline it’s flight.

      exceptions to that are some shotgun and air rifle slugs, that are aerodynamically stable

      The NATO standard 5.56mm bullets changed from a 55 grain to a 70 grain bullet. The heavier bullet had better aerodynamics (actually equivalent to the 150gr 7.62 boat tail bullet) and better retention of velocity and penetration at longer ranges than the 55 grain bullet.

      However the longer bullet and associated tracer bullets, required a faster rotation to stabilise them.

      Hence the changeneral from rifling that gave one complete rotation in 10 inches of travel

      To rifling that gave one complete rotation in about 7 inches of travel.

      As a side note, the larger the calibre (greater the bullet diameter), the less the rate of spin that is needed to stabilise a bullet of a given aerodynamic performance

      So, for roughly the same aerodynamic properties, 5.56mm 70 grain requires around 1 turn in 7 inches

      7.62mm 150gr requires a spin of about 1 turn in 10 to 12 inches.
      A lot of very successful target rifles for that load had a rifling pitch of one turn in 14 inches (that was popularised by Schulz and Larsson).

    • “Could someone explain the differences in barrel twist and how this affects ballistics?”
      To fully answer that would produce book, if not books.
      Keeping simple: every bullet designed as spin-stabilized need proper rotation speed for stable flight. Problem will appear not only if rotation is too slow, but also if it is too fast, c.f. diagram: http://bulletin.accurateshooter.com/2013/07/over-stabilization-of-bullets-why-is-too-much-spin-a-problem/
      Moreover keep in mind that powder charge inside cartridge contain finite quantity of Joules, more Joules you will use for rotation, less will remain for pushing and thus lower muzzle velocity you gets. Soviet 5,45×39 round is example of properly balanced twisting/pushing – it was noted for creating serious wounds due to tumbling. But why it tumbled? Because in flight its rotation speed was bit more than enough to keep it stable, but if it meet obstacle it easily go between stable-unstable border as it was anyway near it.

  7. For those asking “Why did the roller-delay HK system go away…?”, welllll… There are a lot of reasons. Primary one was that the production of those guns was always a bit of a stretch of the system, with the direction modern cartridges took.

    Many people fail to understand the complexities of it all. There’s a subtle set of things that influence what sort of action a particular cartridge, or even loading of the same cartridge works best with. What powder, what projectile weight, shape of the cartridge case–All that influences design. A particular powder combination may have a distinctly different pressure curve, which works well in a recoil-operated system, because of the timing of the pressure impulse, while another will work better with a gas-actuated system.

    Most economical 5.56mm loadings do not work well with recoil-operated weapons; the pressure curves are too short, sharp, and powerful to work well with the roller-delay systems. Roller-delay works best with cartridges like the 7.92×33, which have relatively long and slow pressure curves, and are not generating as much pressure to begin with. The NATO cartridges, following US lead, are all short-fast-high pressure curves, and so you almost have to go with a gas-actuated system that those have an affinity for.

    Many people fail to understand the complexities of all this–Recoil-actuated systems require consistent loads that are tuned to the action (or, vice-versa…) and if you don’t do that, you’re going to experience decreased reliability. Gas systems are more forgiving, and can be designed to be adjustable–Which makes for a more versatile weapon that can use multiple loadings effectively and reliably in its caliber.

    I think HK finally recognized this, and abandoned the gimmick that they’d built their reputation on. Honestly, I think the roller-delay system should have been DOA the moment they went with the high-pressure 7.62 NATO round, and what HK should have done was transition to a roller-locked gas-actuated version. The freakin’ G3 is a much more painful rifle to fire than the FAL, in my experience, and I lay that on the recoil actuation entirely. They’d have done a lot better to recognize the facts–Some things that are mechanically possible are simply not advisable, due to the side effects.

    • The straight-sided 5.56 case might have been a problem for HK too; not a good shape for clean extraction. It’s a shame we didn’t have more 7.62×39 HK rifles to mess with and see if its tapered cartridge inherently functioned better. Then you have its distant and slightly less-tapered relative the 6.5 Grendel…

      • There’s a lot more to the whole thing than just “yeah, make it roller-delayed…”. As you allude to, the case design itself is important.

        People just don’t consider these things when they talk about firearms design. Perhaps, back when it was single-shot blackpowder breechloaders and revolvers, it really wasn’t–You could make anything work in any prevalent design. Once modern propellants came on the scene, along with repeating technology? The scale of the complexities went up exponentially. When you look at the HK line of rifles, one striking thing is this: The fluted chamber. The requirement for that feature is an indicator for just how far out of its comfort zone the 7.62mm NATO was pushing the roller-delay principle.

        Personally, I think a lot of designers go at this stuff from the wrong end, and fall in love with an idea which they then take to ridiculous extremes–The guys at HK are a perfect example. What, precisely, did the roller-delay mechanism bring to a pistol, pray tell? Other than a neat technical exercise, what was the damn point of the P9 series of pistols? To be able to say “Yeah, we made a pistol using our favorite operating principle…”?

        You have to look at the pressure curves, the pressures themselves, the projectile, the mechanics of the case, and a whole host of other things when it comes to designing around a cartridge. Not every mechanism is appropriate for every combination of features, nor is every mechanism cost-effective to implement in a given cartridge. Case in point–CETME “Modelo L”.

        Personally, I think that the process of military small arms design needs to begin with the question of “What effect am I trying to attain with this weapon?”, followed by working up a cartridge and ballistic solution to meet that requirement. Once you’ve managed that, then you start selecting your operating principles, which need to be appropriate to the cartridge selection, and work up your mechanism from there. Attempting to shoehorn in things after the fact, by designing your weapon first and then creating the cartridge, or doing like the Soviets did and adapting a new cartridge into an old rifle? That’s back-asswards, and is unlikely to result in nice things happening. The AK-74 was probably a bit of a fluke, given the actual history of these caliber and cartridge conversions.

        There is a hell of a lot more that goes into weapons design than just cool mechanisms and machinery. The complexities include basic physics, chemistry, mechanics, materials science, and a host of things relating to how all that interacts. You go to pick up a reliable rifle and shoot it, and what you’re actually working with is a product of an entire series of complex interactions that happened behind the scenes, and are sometimes not even fully understood by the people that designed and built the weapon. Witness all the dysfunction around the .40 S&W pistols that were converted over from 9mm, rather than clean-sheeted design-wise… Cartridge and caliber conversion ain’t necessarily as easy as some people seem to think it is. Not on every weapon mechanism, that’s for sure… Although, some can give you a seriously mistaken impression of the possibilities, like the Maxim MGs or the Madsen LMG.

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