We’re going to look at some prototype rifles that never got off the ground. First is the most exotic, the HK G11.

Back in the 80s, the Bundeswehr issued the G3. They hadn’t yet gone over to 5.56mm yet. And they noticed the classic problem of soldier marksmanship: Most soldiers are very poor shots in combat. But what to do about this problem? Automatic fire is hard to control. It can be done with sufficient training, but we’re talking about the average grunt here. A burst of three or so rounds might sound like the ticket, but subsequent shots tend to miss high and right (or left) based on body mechanics and how they interact with recoil. Consistent high right missing isn’t super helpful for getting a higher hit percentage out of a weapon. What if the burst was out of the gun before the recoil impulse got to the shooter? Three superquick rounds. That might give you the spread you’re looking for.

A brief side note: the US Army, with their cool guy M16s noticed a similar problem, and would launch a search for a similar solution, the Advanced Combat Rifle program, based on similar reasoning to the above.

So we want a burst mode that’s super quick. 2,100-rounds-per-minute quick. That’s gonna be tough. And we’re going to want regular rates of automatic fire if we set the selector to full auto. Here comes the complexity. The engineers at HK considered the problem, and decided on an enabling technology: caseless ammo.

Without that pesky case, there’s no extract/eject portion of a normal operating cycle. Less to do means it’s easier to do it all quickly. Yay! Plus, caseless ammo is way lighter than cased ammo. A gain for the logistics geeks. Plus, this would be a SCHV round: 4.73×33 mm¹. This worked to to being significantly lighter than M855 5.56. Rough back of the envelope calculations shows that for about the same weight as a G-3 and 100 rounds of 7.62×51 mm, a soldier could carry a G-11 and 500 rounds of ammunition.

Now let’s get back to America. To get adoption, the US Army wanted the ACR rifle to have a 100% higher hit probability than an M16A2. The G-11 was one of the entrants. Plus it had to be durable and reliable, etc.

A few other notes on the G-11, the rifle to fire these tiny caseless rounds. It weighed about 3.6 kg empty, had a Hensholdt unmagnified reflex sight, and a 45 round box magazine. The G-11 had integrated storage for two additional magazines for quicker reloading, sort of like the redi-mag system. It also had a bottom ejection port for ejection of misfires, or administrative clearing. You might imagine the mechanism to handle the 2,100 round per minute hyperburst plus regular full auto would be complicated and it was. And caseless made it worse. But it worked.

For the hyperburst, the barrel, firing chamber, and magazine assembly were all free floated and recoiled together. Picture a modern howitzer, except much smaller. And the nature of the mechanism meant that you’d get the three projectiles out before that recoiling assembly hit the back of the receiver, which is how they avoided transmitting the recoil for a little while.

Reloading was an interesting design too. Cartridges were in a box magazine above the rotating chamber, and were dropped in tail-first and then rotated 90 degrees into firing position. Turning a cocking lever further would dump a cartridge out the bottom if needed.

Now, let’s talk about the problems. You see, the cartridge case, that pesky bit that we deleted to cut weight and simplify the firing cycle, actually gives us a lot. For one, the cartridge case makes it easy to unload the gun. You can pull pretty easily on the rim of a cartridge case. You can’t pull easily on a compressed powder block. And you’ll want to unload it if a round fails to discharge and you need to get rid of it, or if you’re just done at the range and putting your weapon back.

The cartridge also protects all of your propellant. A cartridge case is relatively durable, and is insensitive to scratches and nicks that might arise from rough handling. It is also reasonably water resistant. No such luck for the caseless round. There were problems with damaged cases and extraction was a pain.

Further, the mechanism got weird because there’s no case to provide a seal at the back of the chamber where the firing pin is, or to seal off the barrel behind the fired bullet. Enter more complexity and a little plastic bit that went at the end of the caseless round to seal the barrel. Barrel sealing problems persisted, though.

Less obviously, the cartridge also provides a great way of getting rid of heat. A bunch of heat from firing the gun goes into heating the cartridge, not the chamber, and then the hot spent cartridge is ejected. Goodbye heat! HK had to contract with Dynamit Nobel for some special insensitive propellant that was then lacquered and used that for the rounds.

Lots of engineering and testing got these problems sorted, more or less. And here’s where the story gets vague. Depending on who you ask, there may or may not have been some thing that weren’t quite sorted. But they were sorted to the satisfaction of the Bundeswehr, who was about to adopt the G-11 in 1990, and there are plenty of documents to back that up. But then the cold war ended. Goodbye Soviet Union, goodbye scary threat, hello expensive reunification. And here the Germans decided against the G-11, which would be massively expensive. Remember, you’d have to set up new weapon and ammo production lines, and the ammo production lines would be entirely new methods. It’s not just a different size of brass/steel cased bullets. NATO wasn’t about to retool with the Soviet Union gone. So instead the Germans moved to (finally) adopt 5.56.

As for the ACR project, well, that was really more of an investigation than a serious replacement effort. And even though soldiers liked the compactness,² reliability, and capability of the G-11, and even though the G-11 exhibited a significantly higher hit probability than the M-16 (or the G-3 for that matter), it did not meet the 100% higher hit probability, and was not adopted.

Where does that leave us, then? Well, it’s time to decide how we rule on this. And the G-11 has an advantage over some of the other weapons we’ll look at in that it’s doing some things that an M-16/SCAR/whatever-5.56-carbine-you-issue-now can’t do. Namely, that fancy hyperburst, and way more ammo for the weight. Plus, since the ammo in question is square, it packs more compactly too. So there’s a logistics win and a weight of fire win. Both of which I really like. Some of the G-11K2 prototypes even were fitted with picatinny rails to mount different optics, so I don’t even have to worry about having that done.

That said, there are some concerns we’d like to put to rest. Since it’s been a while, let’s get a few LRIP guns to make sure the manufacturing process is still good, and do some high round count testing. Plus, I’d like to do some gel tests and intermediate barrier³ tests. Even if that means some projectile design updates to make the terminal effects satisfactory, I can’t forsee any major problems left.

Verdict: Approved for LRIP and phased adoption by the Borgundy War Department Ordnance Procurement Board

1.) Or thereabouts. I’ve seen some variation betwen 4.7-4.9 mm or so.
2.) Despite looking like a space 2×4, troops even liked the ergonomics
3.) Usually sheet metal and tempered glass, i.e. car parts.