Hi guys!
Thanks for tuning in to another video on Forgotten Weapons.com
I'm Ian McCollum and I'm here today at HK's Gray Room in Ashburn, Virginia
Taking a look at a couple of their developmental prototype submachine guns 'cause who doesn't love developmental prototypes?
These are designated the 'SMG', very descriptive, and the improved SMG II, also very descriptive
These were both manufactured-- developed really, in response to a US Navy request for a new submachine gun.
The Navy was looking for something that would be better than-- well better than the MP5
and they had a bunch of requirements, but they're kind of all the standard requirements you would expect.
It has to, you know, be reliable and be durable and shoot well and not weigh too much and be cheap.
In particular, they wanted it to be effective for use with a suppressor.
That seems to have been one of their primary requirements, like, they were planning to run these guns suppressed. A lot.
So they wanted a gun that was really conducive to a suppressor and that definitely influenced HK's design as you'll see in just a minute.
Now HK developed these guns between 1982 and 1985
In fact, If we look here on the back the original, the first model SMG, is a 1983 production gun.
The second pattern one is a 1985 production gun
In the middle of 1985 they were finished and they submitted six individual guns to the Navy for testing.
The Navy kind of took their time; spent about 18 months and in January of '87 the Navy had finished their testing
Six months later, they got around to giving HK the testing report
and the the Navy response to this was basically that
Meh?
Okay?
And they didn't order any.
Because, as is, as very often happens in military testing of this sort of thing
They were hoping to find something that would be a huge step forward and they didn't.
These guns worked fine but they weren't enough of a substantial improvement on the MP5
to justify scrapping what the Navy already had in stock and replacing it.
However, for HK, this wouldn't all go to waste. But, we'll talk about that in a moment.
First, let's take a look at what HK was actually doing with this attempt to improve on the MP5.
All right. Let's start with the first pattern here the 'SMG.'
This doesn't actually follow very many of the form factors of the MP5, which is a little bit surprising
We do see basically the exact same pistol grip and selector switch, but that's kind of where this ends.
So, there are two giant buttons on here
and they are ambidextrous and the bottom one with the square checkering is your magazine release.
This uses a new proprietary magazine, the lock-up is a little bit different because it's not using a paddle
But it is still a 30 round 9 millimeter magazine, obviously based on the MP5 mag, but not interchangeable with it.
Then the top button is actually the bolt hold-open, which for some reason doesn't work on this gun.
But, let's consider that this is, in fact, a developmental prototype. So.
Parts may have been swapped out a bit on this gun resulting in the feature not working
This button does work on the other one so I can show you that, there.
Where the MP5 had its charging handle on the side of the action, as did all of the HK roller locked or roller delayed guns,
the experimental SMG has a top mounted charging handle.
Kind of like a Thompson with a nice...
cut in the middle so that you can see your sights over the top of it.
This is a non reciprocating charging handle
so when you're shooting it, it's not moving around.
The stock is similar to the MP5, sort of, but the butt plate is a bit different. There's a release button on top
And when we push that we can then slide this guy out. It will lock in place back here.
You know, it's functional. It's utilitarian. It's nothing particularly special.
This sort of stock would show up later on the HK MP7.
For what that's worth.
So the sights on this are really kind of something else
We've got a hooded front post here which is pretty typical.
Not even gonna bother letting that come into focus
Then, on the back we have this really large contraption.
It does have an aperture rear sight and then it's got a windage-- giant windage
adjustment knob which is unusual on a nine-millimeter submachine gun
And it's also got a really big range adjustment knob
And this thing goes from 25 meters out to 150 in 25 meter increments.
So, like, really precise, almost weirdly precise, sights and you can flip this in and out
You'll notice here as it says supersonic or subsonic is on the outside like this and
Supersonic is on the inside
When you adjust the sight here what you're actually doing is...
Steps on the spindle of this sight are pushing on that square tab, which raise
the rear sight. It's under spring pressure pushing down.
So as you rotate this it gets lifted up incrementally more and more for the appropriate range
Well, when you push it in, now, it's actually sitting on a separate set of adjustment steps
So your range adjustment is different for-- well, for the inside and the outside.
Which allows you to have two different sight settings for two different types of ammunition
Presumably, you would be running 115 grain ammunition for supersonic and 147 or 158 for subsonic.
So this is part of the response to the Navy's Interest, specifically, in using these suppressed
having two different sight settings for them.
If we look at the muzzle.
You can see that the opening here is hollow and there's threading on the barrel all the way back here
I don't have any of the suppressors to show you
but I can confidently say that the suppressor
telescopes over the barrel and threads on there, for attachment.
Before we move on, we'll go ahead and show you the the markings there
This is SMG and it's serial number 6. Manufactured in November of 1983
Disassembly of this guy is very standard HK. We've got three pushpins here.
Push all of those out
With those pins out we can pull off all of the parts
So, there's our stock with a nice spring buffer to cushion the end of the bolts travel
Fire control group. Hammer fired. So, fires from a closed bolt, which is nice.
Got our recoil spring and
our bolt here.
Oh, I forgot to mention. There are catches here...
because this has a forward assist built into the receiver.
You've got a little tooth that comes out of there
That's just going to push forward on these ratchet notches and
then we can pull off the front handguard as well.
So the body here is metal. Obviously, the bolt and the barrel are metal.
These guys, the front and rear hand guards are plastic
Now, let's move on to SMG 2; the improved version.
This is overall lighter. It adds this interesting control lever. The magazines are not compatible
They're not the same.
These are-- this now uses a plastic magazine, which is definitely lighter.
Still 30 rounds; still not interchangeable with the MP5.
But obviously, geometrically based on it.
Both of these are double stack, double feed magazines.
So we still have the two buttons: the bottom one is of course for the magazine release,
the top one is the bolt release.
So you can't use this to manually lock the bolt open
but, once you have locked it open on an empty magazine, because this did do that,
you can release the bolt with that button.
Both of those as on the SMG 1 are ambidextrous as is the selector switch.
You'll notice this one has a four position selector. So this has a three round burst option built into it.
HK was, you know, real big on on the modularity and the options you could have in fire control groups
with two-round bursts, three-round bursts, full-auto, and kind of any combination thereof.
The stock is basically the same. The parts aren't quite compatible, but they've left the design the same.
One interesting thing they did is put a little flat spring right at the back here. So when you close the stock
you have to give it a little bit of a push to lock it in place.
When you hit the button
It actually pops out a little bit which makes it nice and easy to grasp and extend
That huge, goofy, double drum, gigantic sight is gone having been replaced with a standard
HK pattern drum sight.
However, you'll notice that the apertures on this are a lot bigger
Well, that one is. They've replaced the hundred-meter notch with a really big ghost ring aperture.
And I think that is the sight that I would probably always want to use.
both of these, also, by the way, have STANAG pattern NATO scope attachment points.
Bolt handle is the same here.
Forward assist is the same and the one new thing that we have is this switch
Which-- this is really cool.
This allows you to change the muzzle velocity of your cartridges between high velocity and low velocity
So, how does it do that?
'Cause that kind of seems like "How would you do that?"
Well, let's pull this apart and I'll show you
Disassembly is exactly the same. We've got our three pushpins.
Two on the stock one on the magwell.
Pull these out On the SMG 2, these are all captive pins, which is nice
Pull that
We still have our spring-loaded buffer there
We still have our polymer-framed fire control housing.
This one's a little more complicated because it has that two-round burst feature in it.
The bolt has been lightened a bit. So here's the SMG 2 bolt.
Here is the SMG 1 bolt.
Mechanically identical, they're basically just big, chunky, squarish, bolts
You'll notice the original SMG doesn't have its firing pin in it. That's just a gray room storage thing.
This one does, which is nice.
But they have dramatically shortened the front stem
Lightened it. I suspect this means that the SMG 2 is going to run a little bit faster
The data I have says the SMG 2 runs at about a thousand rounds a minute, which is really quite remarkably fast
I don't have any data for the SMG 1.
All right, and now the cool part. We'll pull
this guy off
maybe?
There we go!
And what do we have under there but what appears to be a little CO2 pressure canister
So, the way this works is that there is actually a series of holes on the bottom of the barrel just in front of the chamber
and when you have this set in this position
which is
'low'
Those holes vent down into this pressurized container
So when you fire, in addition to gas pressure pushing the bullet down the barrel it's also
filling up this big empty chamber. That reduces your chamber pressure.
Which reduces your muzzle velocity.
When you flip that lever up
Now in the 'high velocity position'
Now those vent holes are shut off and so you have the full powder charge
pushing the bullet and you get a higher muzzle velocity.
According to the data I have; this will take a 350 meter-per-second muzzle velocity
and reduce it to 305 meters per second, which is coincidentally, and conveniently, just below the speed of sound
Of course, this is because there is a substantial difference in effectiveness of a suppressor with subsonic versus supersonic cartridges
Even with supersonic cartridges you can reduce most of the report at the muzzle
But, people will still hear a supersonic crack and that can actually even be a bit unpleasant to the ear.
For the shooter.
So if you want a gun, that's really quite silent you have to use subsonic ammunition
or, come up with a clever device like this to reduce your muzzle velocity.
All right, we can actually see those holes
right there,
on the bottom of the rifling just in front of the chamber
So, you can't see them opened or closed because there's a little valve underneath that does that
but those are the gas vent holes that reduce your velocity
Just for completeness sake, here are the markings on SMG 2. Of course, SMG II. This one is serial number 81.
So while they only submitted six of these to the US Navy for testing they did make quite a few more than that.
To get the whole design figured out. And this one is a September 1985 production.
So, I mentioned that the developmental time and effort and work that went into the SMG and the SMG 2
wasn't ultimately wasted even though the Navy didn't buy any of the guns.
And nor did anyone else
Because, most of the work that went into this would end up being used in the UMP project
Creating that guy back there on the wall
Which would be, ultimately, HK's commercial option to try and improve on the MP5
So, uh, it's really cool to get a chance to take a look at two of the developmental
stepping stones between, really, the MP5 and the UMP
and especially that cool velocity reduction switch that's kind of a unique thing.
So, a big thanks to HK for letting me in here to play with their
prototype developmental submachine guns and bring them to you guys.
Hopefully you enjoyed the video. Thanks for watching