Notes From A G36 Armorer’s Course

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HKPro.com forum poster Marine0303 posted the notes from an armorer’s course he took on the H&K G36 rifle. It is complete with pictures, and provides a really good essential understanding of the design and its maintenance requirements:

As I continue my relentless pursuit towards becoming a HK Master Armorer, I thought I would share another of these Armorer Course posts with you all. I wrote this in a similar fashion as several of my previous posts and hope that you’ll learn something new about the G36. I know I sure did.

One of the first post-Cold War weapons, born out of the fall of the Berlin Wall and the cancellation of the G11 program, the G36 represented a new era in weapons manufacturing from Heckler and Koch. With the amount of money that HK had invested into the unrealized G11 project, the company was in need of significant capital infusions and the German military was still in need of a replacement for their aging G3 rifles. As one of the last of the NATO countries to have not converted to the newer and lighter 5.56mm NATO cartridge, Germany was looking to HK for something cost effective and cutting edge. With the purchase of the company by Royal Ordnance, a massive downsizing and focus on transitioning from the legacy stamped steel, delayed roller locking bolt rifles to polymer construction rifles based on the AR18 system, what evolved in the mid-1990s became known as the G36.

The G36 actually represents what is termed as a “family of weapons”, utilizing a very modular approach to construction, where the receiver is the constant, but a wide variety of stocks, optics/sights, barrels, forearms, feed units and other accessories can be utilized to fill the needs of a specific unit or mission. Extremely successful, since its release, many countries have adopted the G36 as their main service weapon to include Germany, Spain and most recently, Saudi Arabia.

Currently there exist three variants of the G36, the G36 with its 18.8 inch barrel, the G36K with its 12.5 inch barrel and the G36C with its 8.9 inch barrel. There was available for a short time, very recently, a G36 CQB which came with a 15.7 inch barrel as well as MG36 with a heavier full length barrel and bipod, intended to fill the Infantry Automatic Rifle or Light Support Weapon. Though the latter saw testing and limited fielding, including initial evaluation for the US Marine Corps Infantry Automatic Rifle project (which HK later won the contract for with the HK416 submission, now designated M27 IAR), the MG36 was discontinued early into the production of the G36 family of weapons.

All G36 variants are designed to function primarily on the NATO 62 grain 5.56mm full metal jacket cartridge and as such, utilize 1/7” twist barrels for optimal stabilization of that round. Those barrels are both cold hammer forged and chrome-lined, leading to both increased accuracy, initially and over time, as well as increased service life. Additionally, HK cold hammer forges their extractors for the bolt. Generally considered a weak point on weapons utilizing this type of bolt system, not so with the G36. The Director of Training and Technical Services for HK Defense mentioned having never seen or heard of a failure of that specific part.

But the heart of the G36 family of weapons is its self-regulating gas piston (pusher rod) system, which follow what athletes refer to as the Minimum Effective Dose or MED (simply defined as the smallest amount that will produce a desired outcome). In other words, only a small amount of the propellant gas from a fired cartridge is required to cycle the weapon. All excess is vented out the front of the gas block.

Clearly seen in the photo below of a close up shot of the cutaway model of the G36 gas block and piston, the tiny port in the top of the barrel allows a small amount of propellant gas to enter the gas block. That pressure forces the gas piston back against the resistance of the pusher rod and spring, which is then transmitted to the bolt carrier, cycling the weapon for the next shot. The piston only moves a short distance (short stroke), as when its tip passes over the gas port, it presents access to the relief vent and the remainder of the propellant gas is forced forward and vented out that relief vent. As all of the heat or fouling associated with the fired cartridge remains in the area of the gas block and not transferred back within the receiver, like in a direct impingement gas system of operation, the rest of the weapon remains relatively cool and clean, increasing the reliability of the weapon and reducing wear and maintenance needs.

The post is long and contains a lot of really helpful information, and I highly encourage our readers to read the whole thing. He finishes his post with his impressions of the G36:

Overall, I believe the G36 series is one of the most underappreciated of the long guns. An incredibly modular and reliable family of weapons, they require very little maintenance and are suitable for a wide range of missions and environmental conditions. In fact, the main wear items for the guns come down to firing pins and gas piston rings. From an Armorer’s point of view, I also found this weapon incredibly easy to work on, with obvious transitions that were carried over to the weapons that followed like the UMP, MP7 and even HK416.

Of course, many of you are wondering, like I am, if HK is going to offer a civilian version of the G36 like we have seen released in Europe. I asked that question and there is no solid answer. The ability is there, but it would involve some US production that is not currently in place. “So, you’re saying there’s a chance…”



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

    I could agree that it’s a very under-appreciated rifle, but there’s obviously reasons for that. The SL8, which was an abomination, was such a far cry from the G36 was not only anti-climatic, but expensive for what it was. Converting one to G36 like features is very time consuming and expensive.

    I know U.S. import laws and German export laws muddled what we in the U.S. could receive, but I’m wondering if they really made enough off the SL8 to even bother importing them.

    I feel privileged to have shot a State Patrol G36 during my law enforcement academy training, even though time and ammo supply allowed us to shoot 10 rounds. I love the design and operation, but the scarcity is what makes it so under-appreciated.

    • joe

      RE: SL8. Please refer to the SL6 and 7. The SLs are “hunting” or “sporting” stocks using the same actions as the base rifles (ie SL6 to HK43/93). With the SL designation, the SL8 isn’t supposed to be G36-like in appearance at all. Though I would have preferred HK went full-on wood (veneer?) stock like the earlier SLs.

      • BattleshipGrey

        The “sporting” stocks were also meant to get around import laws and clearly not meant to look like the G36, but due to laws and other factors, the SLs were the closest thing to a G36 civilians were going to get. Which again, is why I believe the G36 didn’t have a chance at becoming appreciated.

  • Nicks87

    Does he give any reason as to why these rifles have accuracy issues during prolonged firing? Not that I know from personnal experience, just taking a wild guess based on what some “people” have stated on the internet.

    • iksnilol

      IIRC those problems were ammo related (bad copper jackets or something).

      • Tom

        They are being blamed on bad ammo along with massive quantities of very rapid fire.

        Having said that as I understand the theory about poor accuracy is a result of the barrel being attached to the polymer receiver and thus if the receiver heats up to much it becomes soft and the barrel can move.

        • iksnilol

          I know about that. I find in general polymer to be a bad idea, but if I mention that I am suddenly old fashioned and stuck in the past.

          Polymer works for handguards, cheek rests and grips… otherwise metals reign supreme.

          • Joshua

            You’re not alone, I have always felt polymer for receivers is a poor idea for rifles.

          • iksnilol

            It is common sense: If it gets hot then maybe making it out of something vulnerable to heat isn’t such a good idea?

          • Tom

            You worry to much what’s the worst that could happen 🙂

        • I have seen evidence of the plastic “trunnion” deforming with heat, but no scientific study of it. That I would very much like to see.

          • Tom

            I think one of the reasons why so many of us are quite willing to believe that softening of the polymer is to blame are that 1) it makes sense from what we know about most polymers that being that they soften from less heat than aluminium or steel. 2) It would not be the first time that a military has blamed something other than a weapon for its failures 🙂

            But as you say we have no scientific or impartial testing. Time to start a collection to get the Firearms Blog a full auto G36 and a few thousand rounds of ammo 🙂 we will leave it to you guys as to who gets to be the lucky one doing all that shooting.

          • roguetechie

            Nathaniel,

            . We have something almost as good as scientific evidence and testing in the case of the g36 luckily. What might that be you ask? Well shortly after the delft university report hit the net, but long enough that your average person wouldn’t remember what they read from the delft report coverage, the German government quietly cut ALL funding to buy new g36 rifles and even cut the funds for buying spares.

            In the months since they seem to have given away some here and there too. Now because of the nature of military logistics they could have a decade or more before they absolutely MUST buy new rifles of some kind. My gut instinct tells me though that either HK is quietly developing something new which we’ll see as a last second entry into the French rifle competition. Or we’ll just see the German government and HK push hard for France to adopt the 416, and offer to make it a combined buy to achieve economy of scale pricing by the German military adoption of the 416 simultaneously with French adoption.

            Honestly I’d bet money on this scenario personally. It just makes way more sense than either the French or Germans adopting the cz805 or Polish weapon system! Hell even if the respective militaries wanted either system neither the German people nor the French public would allow it to happen!

          • Tom

            As I understand it the Germans have a massive hole in their defence budget. Plus the G36 was in service by 99 so i imagine they have all the rifles they need by now. So I for one would not read too in to this for now.

            On the issue of France’s new rifle if Berretta stick to their promise and make it in France in that’s what the politicians will go for whether the military like it or now.

  • Canadian Vet

    I used to own a SL8 and I’ve regretted selling it for years. It was big, heavy and cumbersome but even with the cheapest ammo I fed it, it was remarkably accurate. Mangled my casings, though.

    And so easy to clean! Having grown accustomed to DI guns and my only prior experience with piston-driven guns being an SKS, every range trip meant 2-3 cleaning sessions to get them cleaned to the standards I was taught. But the HK gas system? I’d drop the piston in a cup of CLP first thing and by the time I was ready to reassemble the rifle all it needed was a quick wipe.

    It is a remarkable system all right.

    • Joshua

      The issue is that the standards we are taught to clean in the Military are not realistic. They are from the days of corrosive powders and primers and meant now days to keep soldiers busy.

      In the field no one follows white glove cleaning regimens, and if you are spending more than 5-10 minutes cleaning your M16 or M4 you are overcleaning to a point that is completely unnecessary.

      Sure op rod guns run cleaner in the upper, but the fouling also does not cause stoppages. It is completely cosmetic in that it is dirty and that bothers some.

  • MPWS

    To put it in short – G36 should have been U.S. service rifle/ carbine/ LSW for more than 20 years by now. It is fully integrated system and on cutting edge, even after those years – without any meaningful competition.

    I consider centre of art of this design in insertion of barrel trunnion into plastic receiver; this being done in controlled automated process. Did not manage to find so far material composition of this part and its respective thermal properties, namely temporary heat absorption capability.

    • Tom

      You can debate if the G36 is a better system or not. But the truth is its just not that much better (if at all) than the M4 to warrant a replacement.

      • MPWS

        For one of many reasons in favor of G36 you can read testimony by Canadian Vet, right below.

    • I have my doubts that the G36 could have held up well against the sort of fully automatic firing schedules sometimes necessitated in Iraq and Afghanistan.

      Further, the XM8 was realistically never going to meet its weight goal.

      • MPWS

        I’d say that source of many misconceptions is how rifle’s role is perceived. If used in long term as LMG, well then is prone to fail. But you know all that.

        XM8… hahaha, that looked to me as ‘practical’ and fashionable as Brazil’s shoes. Actually, many brazil made shoes are really comfy.

        • My biggest beef with the G36(K) is how they got a rifle made almost entirely of plastic minus the critical bits to be almost a pound and a half heavier than an M4, while having a shorter and thinner barrel.

          • Tom

            More than anything else I think that’s what killed the XM8. The aim was to get a weapon lighter than the M4 so they picked a base weapon that was heavier.

            I would add that I think the weight requirements of the XM8 were entirely unrealistic for current technology. And of all the faults one might find with the M4 weight is not one of them. Yes lighter is nicer but not when it compromises reliability and accuracy.

          • Mazryonh

            Do you have any links that go into detail as to why the XM8 failed? It seemed like it had a lot going for it, such as its modularity, the ability to use a folding or completely collapsible stock, and its resistance to dust-induced malfunctions. Its PCAP system looked intriguing as well.

    • Joshua

      We tried that and the XM8 had numerous issues when pushed hard. And it was after all a reskinned XM8.

      Instead running a PiP and fixing the issues with the M4A1 ended up cheaper, and got us a more capable weapon.

      • MPWS

        Appreciate your note; you sound like insider.

        • Joshua

          Lol edited my typo where I said it was a reskinned XM8. It was a reskinned G36 is what I meant.

  • sianmink

    Have a G36C here at my work and I gotta say, it’s easy to work on, easily simpler to maintain and clean than any of the AR15’s. That 8.9″ barrel makes it a bit finicky with the lightweight stuff we use though. Also so loud.

    • iksnilol

      Who thought that a 22.5 cm barrel for 5.56 was a good idea? In 300 BLK it would be really good but for 5.56? My ears ring from thinking about that.

      • Rusty Shackleford

        Not only that, but why name the 8.9″ barrel model the Carbine and the 12.5″ barrel model the Kurz? Did that happen under British management?

        • iksnilol

          Stuff like this is precisely the reason I am wary of Western weapons. Like what are you guys thinking!? Naming a firearm isn’t that complicated, it really doesn’t have to be.

  • n0truscotsman

    I saw the XM8 as a last grasping of straws after it was concluded that the OICW would never be adopted, because the concept was inherently flawed IMO. I argued way back when that 5 lbs goal for the XM8 was a wet dream and the costs and complexity of the OICW was even more questionable.
    Supposedly the XM8 superseded other designs (M4, SCAR, 416) during the 2007 dust tests, but, as brought up by many (and I think it was your article, nathaniel, credited to ‘elements of power’), that those tests in fact raised more questions than they answered and weren’t exactly “objective”.
    I think the main thing going against any effort to replace the M4 is really a catch 22:
    Competitors to the M4 are 5.56 carbines, meaning they are limited to the 5.56 caliber. Any efforts to venture outside 5.56, for a supposed leap in lethality (which I remain dubious of anyways), are not practical due to the costs and diminishing returns. This means that any competitor will have to be a 5.56 carbine, which will not be measurably more lethal than the M4.
    With the current evolution of the M4, it makes the future of any cartridge firing replacement a nebulous affair. MAYBE telescopic case will be the next leap forward.

  • LCON

    If it’s wrong to drool over that G36C… I don’t want to be right

  • Bal256

    Doesn’t sound very much like a “family” of weapons to me, with just shorter and longer barrel versions. The G3 was 7.62×51, and had 5.56 versions and the 9mm MP5 was also based on it. Also there is the PTR-32 in 7.62×39 if you want to count it.

    Does the G36 have a big brother in 7.62×51? Or a little brother chambered in a pistol caliber? Or is the SL-8 just a retarded half-brother to the G36?

  • Mazryonh

    Do you have links to those end-user reports? Maybe even photos of G36 rifles “drooping” in the heat of summertime daylight in Kabul?

  • Mazryonh

    Did you mean to say that the short-barrelled PDW variant of the XM8 was “almost useless” because it had no buttstock, not because of the very short barrel? What about the XM8’s modularity? Would it not have worked in the field either?

    Speaking of folding buttstocks, if that was something they could really use, why not try out the LR-300? That’s one AR-15 variant which has no rear buffer tube and could use a folding buttstock, and supposedly had a gas system that could reduce recoil as well.

    Still, we have something similar to the XM8 Automatic Rifle (the M27 IAR), and negative mounting points like the XM8’s PCAP system are making headway now. So perhaps the XM8 has left behind more of a legacy than most would realize.

    • The lack of buttstock was the reason why I felt the PDW was almost useless, yes.

      It was only later that the XM8 was given a folding stock.

      The LR-300 is architecturally quite different; one might as well adopt an entirely new weapon.

      • Mazryonh

        Perhaps H&K thought that “Our stockless MP5K was a hit, so how about a stockless 5.56mm ultracompact carbine?”

        At least the LR-300 would have had a similar manual of arms to AR-15 types, and if its recoil-reducing gas system worked, it could have offered better shooting performance without the need for compensators or sound suppressors.

        • The LR-300 just uses a DI system feeding into an extended carrier key that acts as a spring guide. I can’t see how that would substantially reduce recoil.