Problems with the H&K G36

Slamfire · May 13, 2015, 10:48 AM

Heckler & Koch G36: the rifle held in all the wrong places
http://www.dw.de/heckler-koch-g36-th...ces/a-18402772

I found the referenced article interesting about the problems the Bundeswehr is having with the H&K G36. New material technologies have been introduced in the last couple of decades, the Glock leading the bow wave for polymers and pistols. After reading this article it seems H&K made use of polymer composites on their G36, to lighten the weapon, but according to the article the plastics are overheating. As far as I know plastics don't expand on heating, such as metals do, instead thermoplastics turn back to a liquid and thermoset plastics char. I suspect the G36 receiver is a thermoplastic as plastics are a lot cheaper to fabricate. Cheap coke bottles and similar items are made of thermoplastics, machines can blow them into a mold. Thermosets take a lot of hand labor and therefore are costly. It has been a long time since I looked at the material properties of thermoplastics, but it is my recollection only a few can be considered "high temperature" and those temperatures were not anywhere near the glowing red of a steel barrel. My guess, based on this article, is that the Germans never required or tested the G36 to the point where cartridges would ignite in the chamber to heat, and therefore their requirements never took into account the heat load that can happen under extended combat conditions. In combat, their weapons were melting.

Before any Americans feel smug about any supposed inherent National superiority, let me show this American made all plastic AR15 receiver. This came out into the market a few years ago. The manufacturer simply copied the dimensions of an aluminum AR15 receiver and poured the thermoplastic into a diminsionally correct mold. It is obvious that the American manufacturer never considered the material property differences between aluminum and discontinuous fiber reinforced plastic, nor the stress paths. The end result was that once loaded up with barrel, bolt, buttstock, these plastic receivers cracked.

However, they were good enough to quickly replace all these design defective receivers with an improved version. If you notice, there is an metal insert where the previous receivers broke.

.

**4V50 Gary** · May 13, 2015, 10:57 AM

The trouble is the G36's plastic cannot take the heat generated from a sustained firefight. The fallschirmjagers who were ambushed were supposedly in a nine hour firefight. Perhaps a metal insert like those used on those thermoplastic AR lowers would improve the G36. I know H&K is taking a lot of flak from its government because of the G36's recent failure.

Fishbed77 · May 13, 2015, 11:04 AM

The problem with G36 accuracy has nothing to do with the durability of polymer, it's because the barrel and sighting system are separated by the polymer receiver. When the receiver heats up, it deforms, leading to a POA/POI shift. This is an apparently obvious design flaw in the G36 and has been exacerbated by the polymer formulations used in the rifle (some of which have been discovered to be out-of-spec).

The US military discovered this basic flaw years ago during XM8 testing. One wonders why it took so long for the Germans to discover and publicly address this issue.

.

marine6680 · May 13, 2015, 04:43 PM

From all the reading I have done on it... I have read several reports translated from the original german...

Originally the polymer was blamed.

Further testing pointed to the ammo.

Even more testing by an independent lab found it was a combination of things.

One: the standard issue ammo used by the German military... it was not meeting the accuracy spec when the ambient temp of the rounds increased. I.E. The environmental conditions... As temps rose, average group size increased, until it eventually stopped meeting the spec. Simply exposing the rounds to sunlight was enough... Heat from firing would affect the rounds as well. So continued firing would lead to lowered accuracy.

Two: The Polymer... This one is actually a multiple issue and I will break them down. Some are material issues, and others design related.

A: The polymer can expand and contract at a different rate than the steel. This causes slight fit issues between the polymer and barrel trunnion, causing a zero shift. As temps increased, the problem grew worse.

B: The expansion affects the sight's zero, due to the fact the polymer expands, and the sights are connected directly to the polymer frame. Laying the rifle in the sun, causing uneven heating, would cause significant shifts in zero.

C: The polymer holds the heat from firing longer, and insulates the components so that they do not cool effectively. This exacerbates the above issues, and the following issue.

D: At some point without the knowledge of the Military, H&K changed the formulation of the polymer used to include a cheaper and more common Thermoplastic. (I want to say PET, but my memory could be faulty on this point) Basically the polymer was no longer a Thermoset plastic (or at least not completely) and was now able to melt slightly and soften at increased temperatures. During firing, the heat would rise above that point. This meant the plastic was soft enough to allow the barrel trunnion to shift position in the polymer frame. I seen a cross section picture of a G36, and you could readily see the evidence of melting and trunnion movement.

During the test, the lab used several other models of rifles. The list of other rifles was not made available last I looked, but was believed to include examples of other popular military rifles from other countries in 5.56... the M4 was believed to be among them.

The lab noted that several other rifles were able to meet or exceed the accuracy specs throughout testing. Though the ambient temp of the German standard issue ammo did decrease accuracy for all rifles in the test.

Using other ammo that did not show such issues with increasing temps, the G36, still could not meet accuracy specs, which pointed to problems other than simply ammo, and lead to the other findings related to the design and materials.

marine6680 · May 13, 2015, 04:56 PM

Quote:

One wonders why it took so long for the Germans to discover and publicly address this issue.

I remember reading somewhere that several government officials and execs at H&K were under investigation for defrauding the government. Basically allowing continued use of the rifle, despite knowledge of the problem or potential for the problem.

Basically they knew for a long time and maybe from the outset that there was a flaw in the design, but pushed it through anyway.

tirod · May 15, 2015, 06:24 AM

The backwards engineered polymer AR lower has nothing in common with the G36 issue.

Their polymer lowers - and others like the SCAR - aren't having any known issues. Those that took the forged design of the original AR lower and simply molded it have learned why other makers - like Glock - have metal inserts, too.

The G36 apparently has the sights mounted separately from the upper receiver and under high heat it's distorting. If the incident reported is accurate, having a nine hour firefight is beginning to sound like the same story as Wanat - blame the gun for a tactical embarrassment.

What's interesting in all the flak about the G36 is nobody is posting pics of how it's constructed - a close up detail of just exactly how the sights are mounted is left out of the hullaballoo.

If someone wants to be informative and enlighten us about the issue, those would be worth the contribution.

marine6680 · May 15, 2015, 06:44 AM

I would have to search but I have found the cross section of the receiver where the trunion is.

I have no such picture of the sights, but as I understand it,the upper is pretty much all polymer, and that includes where the sights sit.

Fishbed77 · May 17, 2015, 12:47 AM

Quote:

What's interesting in all the flak about the G36 is nobody is posting pics of how it's constructed - a close up detail of just exactly how the sights are mounted is left out of the hullaballoo.

Ask and ye shall receive.

http://www.thefirearmblog.com/blog/2...y-intensifies/

This link shows a series of cutaways showing how the polymer G36 receiver is molded around the barrel trunnion. When the polymer "cradle" the trunnion sits in heats up enough to deform, the barrel will shift and lose it's zero, as the sight mount is completely separated from the barrel/trunnion by this polymer (shown by the clear plastic cutaway also at this link).

This also shows why the polymer AR-15 lower receiver analogy completely misses the point.

.

Sequins · May 19, 2015, 12:36 AM

May I please have a link to an article (english preferred, german ok) to the well known incident that predicates tgis discussion? I must confess both ignorance as well as curiosity.

The original forum post is clear, but I'd prefer something more in depth. I may try 150 rounds in full rapid fire from my p30 and if it fails throw it in the trash. I'm carrying it currently and I'm deeply concerned.

marine6680 · May 19, 2015, 08:11 AM

I wouldn't worry about the P30... Completely different construction. You are not likely to see any issue.

Different polymer too.

There is just so much polymer in the G36 design, and how it's designed, make for potential problems. Polymer isn't a problem, this little fiasco with the G36 does not show polymer as an inferior material...

It just shows the limitations and the potential issues if the design isn't thought out enough, or you don't know how to work with the limitations imposed by the material.

It's not a structural problem really. The rifle is tough and robust enough for its duty... But the thermal expansion characteristics were not taken into account. Also poor choice in type of polymer (or formulation of it), lead to additional issues.

Jimro · May 19, 2015, 08:31 AM

To earn the gold "shutzenshneer" (pardon my anglicized phonetic spelling) a Soldier only needs to hit all 21 targets with the G36. That does not include the other weapons of the German military that have their own qual tables.

If the bulk of your military experience is spent firing blanks and then firing for qualification, it could be decades before anyone noticed an over heating problem.

Honestly the Germans ran a marksmanship qualification badge range for US Soldiers in Kandahar a few years back, and the ease US Soldiers had "shooting tight" with the G36 was quoted by Stars and Stripes.

Jimro

Fishbed77 · May 19, 2015, 09:56 PM

Quote:

The original forum post is clear, but I'd prefer something more in depth. I may try 150 rounds in full rapid fire from my p30 and if it fails throw it in the trash. I'm carrying it currently and I'm deeply concerned.

If it fails, send it to me.

It won't though. There seems to be a serious misunderstanding on your part regarding the operation and construction of the G36 select-fire rifle versus your P30 pistol.

themadbomber · May 20, 2015, 08:45 PM

Thats because H&K sux

Fishbed77 · May 21, 2015, 02:54 PM

... and hates you.

May 13, 2015, 10:48 AM	#1
Slamfire Senior Member Join Date: May 27, 2007 Posts: 5,261	Problems with the H&K G36 Heckler & Koch G36: the rifle held in all the wrong places http://www.dw.de/heckler-koch-g36-th...ces/a-18402772 I found the referenced article interesting about the problems the Bundeswehr is having with the H&K G36. New material technologies have been introduced in the last couple of decades, the Glock leading the bow wave for polymers and pistols. After reading this article it seems H&K made use of polymer composites on their G36, to lighten the weapon, but according to the article the plastics are overheating. As far as I know plastics don't expand on heating, such as metals do, instead thermoplastics turn back to a liquid and thermoset plastics char. I suspect the G36 receiver is a thermoplastic as plastics are a lot cheaper to fabricate. Cheap coke bottles and similar items are made of thermoplastics, machines can blow them into a mold. Thermosets take a lot of hand labor and therefore are costly. It has been a long time since I looked at the material properties of thermoplastics, but it is my recollection only a few can be considered "high temperature" and those temperatures were not anywhere near the glowing red of a steel barrel. My guess, based on this article, is that the Germans never required or tested the G36 to the point where cartridges would ignite in the chamber to heat, and therefore their requirements never took into account the heat load that can happen under extended combat conditions. In combat, their weapons were melting. Before any Americans feel smug about any supposed inherent National superiority, let me show this American made all plastic AR15 receiver. This came out into the market a few years ago. The manufacturer simply copied the dimensions of an aluminum AR15 receiver and poured the thermoplastic into a diminsionally correct mold. It is obvious that the American manufacturer never considered the material property differences between aluminum and discontinuous fiber reinforced plastic, nor the stress paths. The end result was that once loaded up with barrel, bolt, buttstock, these plastic receivers cracked. However, they were good enough to quickly replace all these design defective receivers with an improved version. If you notice, there is an metal insert where the previous receivers broke. . __________________ If I'm not shooting, I'm reloading.

May 13, 2015, 10:57 AM	#2
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,832	The trouble is the G36's plastic cannot take the heat generated from a sustained firefight. The fallschirmjagers who were ambushed were supposedly in a nine hour firefight. Perhaps a metal insert like those used on those thermoplastic AR lowers would improve the G36. I know H&K is taking a lot of flak from its government because of the G36's recent failure. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

May 13, 2015, 11:04 AM	#3
Fishbed77 Senior Member Join Date: November 23, 2010 Posts: 4,862	The problem with G36 accuracy has nothing to do with the durability of polymer, it's because the barrel and sighting system are separated by the polymer receiver. When the receiver heats up, it deforms, leading to a POA/POI shift. This is an apparently obvious design flaw in the G36 and has been exacerbated by the polymer formulations used in the rifle (some of which have been discovered to be out-of-spec). The US military discovered this basic flaw years ago during XM8 testing. One wonders why it took so long for the Germans to discover and publicly address this issue. . Last edited by Fishbed77; May 13, 2015 at 11:10 AM.

May 13, 2015, 04:43 PM	#4
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	From all the reading I have done on it... I have read several reports translated from the original german... Originally the polymer was blamed. Further testing pointed to the ammo. Even more testing by an independent lab found it was a combination of things. One: the standard issue ammo used by the German military... it was not meeting the accuracy spec when the ambient temp of the rounds increased. I.E. The environmental conditions... As temps rose, average group size increased, until it eventually stopped meeting the spec. Simply exposing the rounds to sunlight was enough... Heat from firing would affect the rounds as well. So continued firing would lead to lowered accuracy. Two: The Polymer... This one is actually a multiple issue and I will break them down. Some are material issues, and others design related. A: The polymer can expand and contract at a different rate than the steel. This causes slight fit issues between the polymer and barrel trunnion, causing a zero shift. As temps increased, the problem grew worse. B: The expansion affects the sight's zero, due to the fact the polymer expands, and the sights are connected directly to the polymer frame. Laying the rifle in the sun, causing uneven heating, would cause significant shifts in zero. C: The polymer holds the heat from firing longer, and insulates the components so that they do not cool effectively. This exacerbates the above issues, and the following issue. D: At some point without the knowledge of the Military, H&K changed the formulation of the polymer used to include a cheaper and more common Thermoplastic. (I want to say PET, but my memory could be faulty on this point) Basically the polymer was no longer a Thermoset plastic (or at least not completely) and was now able to melt slightly and soften at increased temperatures. During firing, the heat would rise above that point. This meant the plastic was soft enough to allow the barrel trunnion to shift position in the polymer frame. I seen a cross section picture of a G36, and you could readily see the evidence of melting and trunnion movement. During the test, the lab used several other models of rifles. The list of other rifles was not made available last I looked, but was believed to include examples of other popular military rifles from other countries in 5.56... the M4 was believed to be among them. The lab noted that several other rifles were able to meet or exceed the accuracy specs throughout testing. Though the ambient temp of the German standard issue ammo did decrease accuracy for all rifles in the test. Using other ammo that did not show such issues with increasing temps, the G36, still could not meet accuracy specs, which pointed to problems other than simply ammo, and lead to the other findings related to the design and materials. Last edited by marine6680; May 13, 2015 at 04:51 PM.

May 19, 2015, 12:36 AM	#9
Sequins Senior Member Join Date: October 14, 2014 Posts: 394	May I please have a link to an article (english preferred, german ok) to the well known incident that predicates tgis discussion? I must confess both ignorance as well as curiosity. The original forum post is clear, but I'd prefer something more in depth. I may try 150 rounds in full rapid fire from my p30 and if it fails throw it in the trash. I'm carrying it currently and I'm deeply concerned. Last edited by Sequins; May 19, 2015 at 12:41 AM.

May 15, 2015, 06:24 AM	#6
tirod Junior member Join Date: January 21, 2009 Posts: 1,672	The backwards engineered polymer AR lower has nothing in common with the G36 issue. Their polymer lowers - and others like the SCAR - aren't having any known issues. Those that took the forged design of the original AR lower and simply molded it have learned why other makers - like Glock - have metal inserts, too. The G36 apparently has the sights mounted separately from the upper receiver and under high heat it's distorting. If the incident reported is accurate, having a nine hour firefight is beginning to sound like the same story as Wanat - blame the gun for a tactical embarrassment. What's interesting in all the flak about the G36 is nobody is posting pics of how it's constructed - a close up detail of just exactly how the sights are mounted is left out of the hullaballoo. If someone wants to be informative and enlighten us about the issue, those would be worth the contribution.

May 15, 2015, 06:44 AM	#7
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	I would have to search but I have found the cross section of the receiver where the trunion is. I have no such picture of the sights, but as I understand it,the upper is pretty much all polymer, and that includes where the sights sit.

May 19, 2015, 08:11 AM	#10
marine6680 Senior Member Join Date: July 24, 2012 Location: Parker, CO Posts: 4,594	I wouldn't worry about the P30... Completely different construction. You are not likely to see any issue. Different polymer too. There is just so much polymer in the G36 design, and how it's designed, make for potential problems. Polymer isn't a problem, this little fiasco with the G36 does not show polymer as an inferior material... It just shows the limitations and the potential issues if the design isn't thought out enough, or you don't know how to work with the limitations imposed by the material. It's not a structural problem really. The rifle is tough and robust enough for its duty... But the thermal expansion characteristics were not taken into account. Also poor choice in type of polymer (or formulation of it), lead to additional issues. Last edited by marine6680; May 19, 2015 at 08:18 AM.

May 19, 2015, 08:31 AM	#11
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	To earn the gold "shutzenshneer" (pardon my anglicized phonetic spelling) a Soldier only needs to hit all 21 targets with the G36. That does not include the other weapons of the German military that have their own qual tables. If the bulk of your military experience is spent firing blanks and then firing for qualification, it could be decades before anyone noticed an over heating problem. Honestly the Germans ran a marksmanship qualification badge range for US Soldiers in Kandahar a few years back, and the ease US Soldiers had "shooting tight" with the G36 was quoted by Stars and Stripes. Jimro __________________ Machine guns are awesome until you have to carry one.

May 20, 2015, 08:45 PM	#13
themadbomber Member Join Date: February 5, 2015 Posts: 24	Thats because H&K sux

May 21, 2015, 02:54 PM	#14
Fishbed77 Senior Member Join Date: November 23, 2010 Posts: 4,862	... and hates you.