Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and I am here today at Morphy's taking a look at an HK21E.
This is the fully modernised version of HK's light machine gun
based on their sort of universally applied roller-delayed blowback system.
So, this dates to the early 1960s.
Of course at that point HK had got a contract to manufacture G3 rifles for the German military,
and they got part way through that contract and decided,
"You know what? We need to have like a companion light machine gun,
or squad automatic weapon, to go along with our rifle."
They were looking at selling ... the G3 rifles,
as well as what would become HK21s widely on the international market.
And it makes sense that if you're going to make a rifle
you make a light machine gun to pair with it.
This is something common. We'll see it with the FN FAL
where they had a heavy-barrelled squad automatic version of the FAL.
Colt had a number of developments for light machine guns, the CMG-2 and CMG-3,
that it tried to market alongside its AR-15/M16 rifles.
And HK had the same idea.
Now HK would be very successful in scaling
their roller-delayed mechanical system both up and down.
So scaled down to 9mm you get the MP5 submachine gun, and all of its variations.
You have the G3 rifle as well as the HK33 in 5.56, and all of those variations in length and such.
And then scaled up with a heavier-duty receiver, a heavier barrel,
a quick change barrel, and a belt feed mechanism and you get the HK21.
I've discussed HK nomenclature a bit in the past.
Suffice to say at this point, the first digit tells you what type of firearm it is.
So in this case 91 indicates a shoulder rifle,
21 indicates a ... belt-fed light machine gun.
Worth pointing out, HK11, the numeral "1" is the first digit,
indicates a magazine-fed automatic rifle.
... And then the second digit describes the calibre.
So in this case 21, "2" means a belt-fed light machine gun,
the "1" digit indicates that it is 7.62 NATO calibre, last digit being "3" indicates 5.56.
So HK would develop the HK23 as well, which is basically the same gun here in 5.56.
Anyway, I'm getting ahead of myself.
1961 they come out with the HK21, and at that point it is very much just a G3 receiver,
kind of modified to have a quick-change heavy barrel and a belt-feed mechanism.
And the first major ... buyer is Portugal.
Portugal has adopted the G3 as its standard rifle,
and they go ahead and adopt the 21 as a standard light machine gun.
They designate it the m/968 in 1968.
The German military would never adopt these large scale
because they already had a universal machine gun they were very happy with,
that being the MG3, an updated version of the MG 42.
This was more for smaller countries, second-tier military forces,
who were going to be ordering things not from their own domestic
arms manufacturers or state-owned arsenals, but from export companies like H&K.
So, in the 1970s they would go through and make some updates to this
that resulted in the HK21A1.
The US actually tested this in 1974, but opted not to adopt it.
And then in the early 1980s would come the HK21E, the "E" is for export model.
And it includes improvements and strengthening of basically all the components.
So everything from the recoil buffer in the buttstock being improved,
the receiver was actually lengthened about an inch
to allow ... a longer bolt travel which reduces felt recoil.
The barrel shroud at the front was extended a couple of inches, that gives you a longer sight radius.
The barrel was made a little bit longer, the bipod was improved.
The attachment mechanism for the belt-feed system was improved,
the belt feed itself was improved.
They added ... a mechanism for attaching a belt box to the gun.
The barrel removal handle was enlarged.
The fire control group went from ... safe, semi, full,
to safe, semi, three round burst, full (for those who wanted it at least).
They added a forward assist to the receiver.
... Like, the whole gun got overhauled.
It actually gained about 3 pounds in weight in this process.
The original HK21s were 7.9 kilograms, which is about 17.5 pounds.
The 21E version has inflated that to like 9.35 kilograms which is 20.5 pounds.
So it picked up a couple of pounds along the way.
One of the elements that really sets the
HK21 apart from a lot of the other light machine guns out there is its modularity.
And this is in particular true with the 21E version.
It can actually be readily swapped between .308 and 5.56 calibres.
It can be swapped between a number of different barrel lengths, that's not difficult.
And it can also actually go to magazine feed very easily.
So, let me show you how all that actually works.
One of the design elements that came about with belt-fed machine guns was the top cover.
The idea that you have a ... piece pinned at the front that will open up
and allow the shooter access to all of the internals of the gun from above,
where they are easy to look at, easy to manipulate, easy to fix if anything breaks.
And this has been kind of standard for belt-fed guns for nearly 100 years now.
However, if you're going to take an existing platform like
the stamped sheet-metal receiver of a G3 rifle
and make a belt-fed version of it, you can't really do that.
Adding a top cover to an HK roller-delayed gun would completely change the ... receiver architecture.
So instead they put the belt feed mechanism on the bottom here.
And in true HK style it is actually modular and detachable.
So before I take it off actually I will show you,
there is a latch here which allows you to drop the bottom half of the feed mechanism.
You do that for loading and for safing the gun.
Having this open ensures that there is not a round in the feedway.
Now these are closed bolt firing guns just like all of the other HK ... roller-delay family of firearms.
So that has some pros and some cons when it comes to a light machine gun.
The benefit is it tends to be a very accurate gun in semi-automatic fire
because the bolt's already closed when you pull the trigger.
The barrel is fixed because it's not a recoil operated gun, so semi-auto - very effective.
However in trade-off you have less cooling ability than a traditional open bolt gun
because you don't get air circulation through.
If you fire enough to heat up the barrel to the temperature that a round can cookoff,
well, a closed bolt firing gun is always going to come to rest
with a cartridge sitting in the chamber waiting to fire.
So on an open bolt gun, no matter how hot the barrel gets,
you'll never have a cookoff because rounds aren't sitting in the chamber.
With a closed bolt gun they are, and so a cookoff is a potential hazard.
It's just an issue that you have to be aware of with a gun like this.
Now you may have noticed that the bottom of the belt feed
module here is open and exposed to the elements.
And the reason for that is that there is a belt-feed box
that sits on top of it here and closes that off, there we go.
So with the box in place you no longer have all that dirt or mud exposure.
The box here, by the way, has this kind of cool system where there's a little spring clip here
that keeps the box closed.
You've got just enough space for a starter tab of a belt.
And when you want to use it, you lift this catch up,
and then this will open,
just enough like that to let the belt come out without opening a huge gap in the box.
To remove the belt box, because it does latch in place,
you have a ... lever here that allows you to take it off.
Now the left side of the barrel shroud is solid with vent holes here for airflow.
We have our charging handle which functions the exact same way as on a G3 rifle,
it's just a little bit bigger to give you a better grasp on it.
I'm going to go ahead and lock this open,
like so.
Now you have to have the bolt ... locked open to change the barrel
because the extractor actually sits in a little cutout in the breech face.
So, once you've got the bolt locked open,
you can push this in, rotate the barrel up just slightly,
and then it slides forward.
And using this big plastic handle, you can grab it and pull it out of the gun.
Replacing the new barrel is just as easy.
I have here an HK11 length barrel. Slide it in, comes in there,
and just snaps down and locks into place.
And the barrel's changed and ready to go.
You have a nice detachable bipod on the front.
This mounting system gives you a nice amount of pivot (or it does when the bipod's not folded up).
Kind of inspired by the MG 34, MG 42 system, so the legs just snap out.
In order to retract them you have to push the button in,
and then snap the leg back.
These legs are fairly simple, they're not adjustable for length,
they're not adjustable for any angle other than locked in the straight open position.
And then you get a fair amount of pivot on the gun,
as well as a little bit of play here.
But you can ... pull solidly into the bipod.
Now the modularity of the gun really comes into play when you want to change calibres or feed systems.
So of course you saw how you can change the barrel out.
There is a single pin, right here, that locks the whole feed assembly in place.
So ... I can pull that entirely off.
They do have ... belt-fed feed blocks in 5.56 calibre, this is in 7.62 NATO.
But the two are completely interchangeable, their external dimensions are the same
even though the cartridges are different in length.
What we can do here, should you want to, is
replace that belt-feed mechanism with a magazine feed tower.
As far as the gun's concerned no big deal, it doesn't really care [apart from swapping the bolt].
Cartridges present here and feed out of magazines just fine.
So we can use that same pin, lock this (there we go) lock that in place there.
There's a little spring catch right here that holds this up in position.
And then you can use standard 20 round box magazines in the gun.
Now originally when HK designed the HK 11,
which ... used this shortish barrel length and was specifically intended for box magazines,
they actually developed a double drum magazine.
But the HK11 was never a particularly successful gun, not like the 21 and 23,
and so those drum magazines were dropped from production and are really quite scarce.
A couple of other items to take a quick look at here.
There is a forward assist on the receiver. This was added as part of the 21E upgrade program.
You can see the ratchet cuts here on the bolt.
That is more for allowing you to drop the bolt quietly.
Not such a big deal on the AR pattern, but HK requires the bolt to be going fairly fast
to actually lock those rollers into battery at the end of travel.
And if you want to do that quietly, well, that's difficult unless you have a little manual lever
that you can use to force the ... bolt into battery after letting it down gently. So that's there.
There are scope mounting blocks here, that's part of the 21E upgrade as well.
The drum sight is not used on the 21, instead it has a single rear aperture sight
and a big ol' elevation drum that allows you to crank it out to 1,100 metres.
Or all the way down to 100.
The stock has this clubfoot design that you would expect for a light machine gun.
The original HK21s in the 60s did not, they used a standard G3 stock.
This was another one of the improvements,
actually an improvement from the 21A pattern in the 70s, that carried over to the 21E.
Notice also we have a pair of little trunnions back here
that are for mounting the gun on a pintle or tripod mount.
The front part of that system is this lug right here.
So this can be used as a vehicular gun,
as a sustained fire tripod mounted gun,
again, part of the modularity of the system.
And before we wrap this up, I will go ahead and show you the internals.
So disassembly is just like any other rifle in the family.
Pull the pins out, store them there in the buttstock.
Once I pull the stock off, we of course have a recoil buffer in the stock.
That was something that was strengthened and improved for the 21E.
And we can then pull the bolt carrier assembly out the back of the gun.
So there's our captive recoil spring.
And there's our bolt carrier.
If you are familiar with the G3 rifle, there's really no surprise here.
The one difference is there is a track on the bottom of the bolt carrier
that acts as part of the feed system for the belt feed unit.
So ... this will cause the belt feed unit to actually cycle,
as the bolt goes back and forth it pulls rounds up on the belt.
So these parts are not interchangeable with the G3.
In fact basically none of the components, except maybe some small things like pins,
are actually interchangeable with the G3.
The mechanical system is the same, and the parts are modular within the HK21E family itself,
but not with the rifles.
The advantage to having this system if you use G3 rifles
is that your operation and training ... protocols are basically the same across the whole platform.
Troops who are familiar with the G3 rifle will be fairly familiar with the HK21 pretty easily.
I do also want to show you the fire control group.
Note that it does not have a pin in the front.
This is an HK21 standalone fire control unit.
Again, where a lot of the ... roller delayed family is interchangeable,
the fire control unit here is not.
One of the other changes that was made with the 21E was
the addition of a burst setting in addition to full full-auto.
So, that's what you got there.
You can see the receiver here with its reinforcing up here as well as back there.
And that's about it.
There you go, there is an HK21E field stripped out,
with both belt and magazine assemblies.
Basically this is a 21E and also an HK11E.
The HK21 would prove to be a fairly successful commercial venture for HK.
By 1977 they'd sold some 20,000 of them across 20 different countries,
that's nothing to sneeze at.
They had a number of countries that purchased licencing rights to manufacture the gun domestically.
Those would include Portugal and Mexico, and maybe another - not entirely sure.
The gun today has been replaced in HK's catalogue lineup
by the MG4 and MG5 in 5.56 and 7.62 respectively,
but there's still a lot of popularity for the old stamped-steel roller-delayed system.
Just as we see in submachine guns, where they can't seem to stop selling MP5s
despite having the UMP available.
So these certainly have a lot of cachet here in the US.
People think they're extremely cool guns because, frankly, they are extremely cool guns.
I have a shooting video that I did on one of these that I'll link at the end of this video.
So if you're interested you can check that out, that was done
courtesy of HK and Trijicon, so thanks to them.
And of course, thanks to Morphy's for giving me access to this particular one
with its whole smorgasbord of accessories and adapter parts to show to you.
Hopefully you enjoyed the video, thanks for watching.