Our thanks to the collection that holds the G11 for the privileged and nerve-wracking opportunity to field strip it and take a look inside. If you’d like to know more about the history of the G11’s development you can check out our video and full blog on it here. Vic has done a great series of videos looking at the G11 and the other prototype rifles from the US Army’s abortive Advanced Combat Rifle trials – you can find those here.
In this blog we’ll take a closer look at some of the G11’s components, for a demonstration of dissassembly and and explanation of how the rifle works in principal check out the video above.
Firstly, lets take a look at the exterior of the rifle. The weapon has a box-like polymer coated outer shell. The shell is made up of three parts, with the butt assembly and forend locking into the centre assembly which includes the pistol grip, trigger mechanism and optical sight. The forend and butt are locked into the centre assembly by plastic locking tabs. While stiff and somewhat difficult to depress the tabs are reportedly prone to breaking.
Before we look at the G11’s internals lets take a look at the shell components. Here we can see the inside of the forend, we can see a metal (aluminium I believe) barrel tube into which the barrel slides.
Below is a photograph of the rear of the centre assembly looking forward, the small white circle (sadly slightly out of focus) is the bushing the barrel protrudes through into the forend.
Next we have a view of the inside of the rifle’s butt assembly. Note the scuff marks on the inside where the centre assembly has scrapped the plastic. We can also see the locking tab windows which are on the top and bottom of the butt.
Inside the butt we can see the ‘toothed wheel’ and ‘sealing gear’ which are turned when the cocking piece is rotated. These plastic pieces act directly on the action. Behind that is the gas escape valve, which will tap off excess gas if over pressure problems occur with the rifle.
The first step to disassembling the G11 is ensuring the weapon is clear by pushing the cleaning brush up into the breech.
Lets now take a look at the rifle’s action up close, below we can see the G11 with its forend and butt assembly removed. Next to it is the breech cylinder and control disk.
Here are some photos of the action from various angles:
Here’s some close ups of the breech cylinder and control disk:
Here are some close ups of the various parts of the action:
According to the 1989 armourer’s manual, provided for the ACR trials, the G11 is made up of a total of nearly 450 individual parts. 144 of those make up the G11’s breech assembly.
With the breech and barrel assembly removed from the centre assembly here’s a diagram I put together showing most of the component parts of the G11’s action:
Next lets take a look at the G11’s barrel assembly with its recoil management system and gas piston:
Finally, here’s a photo of the G11 broken down into its major component assemblies: magazine, forend, centre assembly breech & barrel assembly and butt stock:
HK G11- ACR. Armourer’s Manual for Maintenance of Repair of Rifle, 4.92mm, ACR, March 1989 (source)
Vic kicks off his series looking at the US Army’s ACR trials rifleswith a look at, not one but two versions of, Heckler & Koch’s advanced caseless ammunition assault rifle – the G11. This video is an introductory overview, we’ll be delving into the G11’s insanely intricate and wonderfully complex action in later videos!
There are few experimental weapons that have cultivated myth and reputation like Heckler & Koch’s G11. The product of decades of research and development into what was hoped would be the next evolutionary step in small arms design. The G11 was Germany’s attempt to combine advanced caseless ammunition with a weapon system which could increase the average infantryman’s hit probability. The G11’s action has three distinct modes of fire and uses a complex action and buffer/recoil system to achieve a high rate of controlled fire.
The program began in the late 1960s as part of a NATO initiative, however, it became a primarily Bundeswehr project and over two decades the design evolved substantially. The project sought to increase the hit probability of the individual infantryman. Heckler & Koch’s approach to this problem was the most radical. Working with Hensoldt to develop an integrated optical sight and with Dynamit-Nobel to create a new kind of ammunition.
Numerous studies and theoretical designs were worked up but by the mid-1970s the base design of what would become the G11 was cemented. The design team included Gunter Kastner, Dieter Ketterer, Tilo Moller and Ernst Wossner – all of whom are credited in H&K’s 1976 patent protecting the G11’s rotary action.
The G11 went through dozens of iterations throughout the 1970s and 80s, with the first firing prototypes ready by 1974. Both the design and the ammunition also went through a number of changes.
The revolutionary ammunition was developed by Dynamit-Nobel AG.
The 4.73x33mm round which was finalised comprised of a solid propellant material body which encased a primer, booster, projectile and a plastic nose cap. Dynamit-Nobel developed the High Ignition Temperature Propellant (HITP) in an effort to prevent accidental ignition (cook-off) of the ammunition’s outer propellant body.
The G11 fed from 45 or 50-round horizontal, single stack box magazines which fed rounds into the action at 90-degrees. The rounds were then rotated into alignment with the breech by the rifle’s action.
The rectangular shape of the Dynamit-Nobel ammunition was more efficient and better suited to storage than conventional circular rounds. The positioning of the magazine along the top of the weapon, parallel to the barrel, also in theory helped minimise the rifle’s profile and reduce encumbrance for the soldier equipped with the weapon.
The G11 is a gas-operated weapon with gas being tapped from the barrel, to cycle the rifle’s cylinder drive system, which rotated the breech through a series of cams and gears. At the heart of the G11 is a complex rotary action. Rotating actions themselves are not a new concept with the earliest dating back to the 17th century, such as the Lorenzoni system.
The G11’s rotating breech was patented in late 1976 by Heckler & Koch. While our initial video does not go into detail on how the G11 operates, we will be covering this in later videos, this article will explain the action in more general terms.
Below are two diagrams showing the internal layout and major components of the G11 from a March 1982 draft of the ‘Rifle, 4.92mm, ACR’ armourer’s manual (source). It shows the major assembly groups and also a component list for the breech assembly.
From the diagram we can see the various action parts which feed the projectile into the breech, lock the action and ignite the round. We can also see the counter-recoil system beneath the barrel.
The G11 used a counter-recoil buffer mechanism to allow high rates of burst fire. When firing three round bursts the weapon send the rounds downrange at a rate of ~2,000 rounds per minute, only when the last round has left the barrel does the barrel and action begin to recoil inside the stock along a central guide. When in sustained fire the rate of fire is closer to ~460 per minute.
The buffer spring below the barrel is compressed as the recoiling barrel and breech assembly moves. In sustained fire the buffer spring is partially compressed with each round, but in burst fire the buffer is compressed to its maximum hitting before the buffer housing (which is when recoil from the burst is felt by the operator), this is described as having the barrel and breech assembly ‘float’.
To ready the weapon to fire a magazine was loaded into the magazine channel on top of the G11, a magazine dust door, which automatically closed when unloaded, was depressed as the magazine was pushed home. The cocking handle on the left side of the butt was then actuated. The operator rotated the handle 360-degrees counter-clockwise until the weapon was cocked (essentially like winding a clock). The same process will eject any rounds left in the chamber once the magazine has been removed.
Gas tapped from the barrel cycles the cylinder drive system with gas pushing a piston back to act on a series of gears which rotated the rotary breech from horizontal to vertical to allow a new cartridge to drop into the breech. There was a vent for high pressure gas underneath the butt stock this prevented pressure build up and mitigated some of the thermal build up.
The G11 K1 was tested by the German Army in the late 1980s with adoption planned for the early 1990s. Heckler & Koch continued to develop the G11, entering the G11 K2 into the US Army’s Advanced Combat Rifle (ACR) trials alongside entries from Steyr, AAI and Colt [all of which we will examine in upcoming videos]. However, the fall of the Berlin Wall in 1989 and the collapse of the Soviet Union in 1991 meant that West Germany no longer had the huge amount of funds needed to field the G11. At the same time the ACR program ended inconclusively and the G11 project was finally abandoned.
The extreme complexity of the design, the inadequacy of the weapon’s ergonomics and its inevitably high production cost casts doubt on whether the G11 would ever have seriously been considered for widespread adoption. Regardless of this the G11 is a fascinating footnote in small arms history representing a false start along a technological avenue which, with the Lightweight Small Arms Technologies (LSAT) program, may still prove fruitful. Heckler & Koch and Dynamit-Nobel’s ambitious design marks one of very few serious and potentially successful attempts engineers to overcome the plateau that firearms technology is currently stuck on.
Stripping the HK G11
Matt recently had the opportunity to disassemble a G11 and get a look inside the action. In this special video and accompanying full-length article he explains how the rifle strips and how it works! Check out the video here.