Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, I am here today at the Royal Armouries, the National Firearms Centre in Leeds, England.
I'm here courtesy of ARES, Armament Research Services.
Today we are taking a look at a very cool one of a kind British post-World War Two light machine gun.
This is the Korsac light machine gun, also known as the EM-1,
although that designation would later be applied to a different rifle.
Which we're also going to take a look at while we're here.
But, what's interesting about this is it was designed by actually a Polish émigré firearms designer.
Of course when Germany occupied Poland a lot of people escaped from the country.
And there were a number of Polish firearms designers, quite talented Polish firearms designers,
who made their way to the UK and got to work designing firearms there.
It wasn't just Polish, but Poles among others.
Well Korsac right at the end of World War Two got his hands on some German FG-42 rifles,
and basically copied them in a bullpup configuration. And that's what this rifle largely is.
It's chambered for 8mm Mauser and it's basically a bullpup FG-42, which is extremely cool.
Now we have a second pattern FG-42 here that we are going to use as a comparison,
because we're going to go ahead and pull this apart, and take a look at just how closely its parts ... compare to the real FG-42.
A little bit of background on this rifle, there's not a whole lot to say.
Development began in 1945 and the project was terminated in 1947, relegated to museum status.
A total of 2,500 pounds sterling were put into this effort and there were only two guns made.
There was one that was in the white, and there was one that was in firing condition.
And this is the firing condition gun, and it definitely shows some wear on some of the parts.
The reason that the project was terminated was there were several other
projects along these lines, bullpup rifle projects, at Enfield at that time that were clearly progressing better.
And so they looked at this one, they said, "Well, we don't really think this is ultimately going to be a successful project.
So we're going to cut this off and we'll continue working on some others."
And this would definitely contribute some important lessons towards what would become the Janson EM-2 rifle,
which would eventually, for a very short time, be adopted as British Rifle Number 9.
With all that in mind, let's take a closer look at this, and then let's pull it apart.
The Korsac rifle here weighs in at 11.5 pounds, that's 5.1 kilos.
And has a remarkably long barrel of course because it is a bullpup design.
I don't believe this is the original magazine, but it took magazines that were basically of the 7.92 Bren variety,
which means ZB-26 magazines. And apparently the magazine held 18 rounds, where the ZB magazines held 20.
A lot of elements on this rifle were copied either loosely or very strictly from the FG-42, the sights included.
These are folding sights, just like on an FG-42.
Let's take a closer look at the controls on the other side.
Alright, for reference sake here is an actual FG-42. This has a safe and fire lever,
and then it has a single shot and a full-auto switch.
And in order to switch from single to full-auto you actually have to lift this
pin up against spring tension, and then rotate it around. So that was the FG-42 set of controls.
And the Korsac here is identical. We have a safe and fire lever.
And then we have single shot and full-auto.
And this again is a spring-loaded plunger that you have to lift up to move back and forth.
Now on the FG-42 if you are in semi-auto mode, the gun fires from a closed bolt.
If I switch to full-auto, like that, now the gun fires from an open bolt.
Predictably the Korsac works the same way.
So right now if I lock this open, I'm on full-auto so it fires from an open bolt,
like so. If I switch it to semi-auto
it no longer locks open, because it is now set to fire from a closed bolt.
Disassembly of the Korsac is going to begin at the rear end here.
... The butt plate has this spring-loaded button on it,
going to push that in, and then rotate the butt plate down about 30 degrees, and then it comes out
along with its very long recoil spring.
We have a series of ... interrupted threads right here that lock the butt plate into the back of the receiver.
With that out, we can now pull the bolt and bolt carrier assembly out of the gun. I'm going to push this back.
... When you first push the bolt,
you're actually unlocking the bolt and cocking the firing pin spring, right there,
and then it becomes nice and loose. ... Pull that all the way to the back.
The charging handle then comes out, and it's interesting to note that the charging handle has this little notch in it
into which the plug on the end of the recoil spring fits
and it's this plug that prevents the charging handle from coming out.
So once you take the spring out and its guide plug at the end, the charging handle can just fall out of the gun.
Now we can pull this out the rear.
There is our bolt and piston assembly.
We're going to take off the trigger mechanism, we're going to do that by removing this pin.
You might expect that the pistol grip itself comes off, but it actually does not.
Once that pin is out then this
trigger assembly and front grip comes off.
And we have our two sears there. So there's our semi-auto sear,
and when I move this, now I have a full-auto sear.
Next up, one of the cool features of the Korsac is that the barrel is actually based on like a Bren gun barrel,
and the whole thing comes out of the receiver. So I can rotate the gas block here,
wiggle this a bit,
and our entire barrel assembly comes out,
leaving us with (oh, and this, we'll get to this in a moment),
and there is our receiver.
Being able to have the barrel separate makes the receiver much easier to manufacture,
because you can basically drill all the way through everything, instead of having to have it
blind at one end where the barrel locks in.
One more bit to take a closer look at here is the bolt assembly.
This is very much like an FG-42, we'll compare them in just a moment,
but first I'm going to go ahead and disassemble this.
And I do that by taking this rear assembly, and I'm going to rotate it over to this side.
There are a pair of cutouts right here where this rear piece can come off, like that.
Then the firing pin spring can come out.
(There we go.) And then the [op rod] has a little claw that holds onto the firing pin,
... I'm sorry, the op rod has a claw.
Pull the op rod off, and the firing pin can come out the back of the bolt, and there is our bolt body.
Here we have a set of FG-42 parts, and the Korsac EM-1 parts.
And you can see all of these little features are the same. For example,
we have this pin in the end of the recoil spring that locks the charging handle in place.
That's the same on the FG-42, there's a little cutout here that fits the plug on the end of the recoil spring.
This was actually something that was updated throughout the development of the FG-42.
Early rifles did not have that, they just relied on friction instead of having a cutout.
And that led to charging handles kind of flying out of the gun intermittently, which was a problem.
And then these both share this rather unique system where
the op rod, the piston and op rod, have this claw that holds the firing pin fixed in position.
And it leads to a rather unusual mechanism of firing where the sear is actually holding this slightly back inside the bolt.
When you pull the trigger, this entire assembly jumps forward maybe half an inch to fire,
because the firing pin is fixed like this.
So when these guns are operating, this is the unlocked position with the bolt lugs vertical.
And as this goes forward this cam track forces the bolt to rotate,
and it's going to sit in approximately this position when it's cocked and ready to fire.
And that means the bolt is locked in place, but the firing pin doesn't extend through the bolt face.
Then when you pull the trigger the bolt is already locked in place, it doesn't move,
but the recoil spring is pushing on the gas piston and it snaps forward like that,
and the firing pin protrudes through the bolt face and fires the cartridge.
Now these fire from, as you saw, the open bolt when they are in full-auto,
which means that this whole assembly is held in a rearward position like this, unlocked and totally open.
When you pull the trigger at this point, this whole assembly goes forward and
again the breech face is going to hit the barrel, that stops the bolt,
forces this to rotate. But on a full-auto position nothing stops the bolt in this position,
and instead it goes all the way forward like that, fires,
and then gas pressure on the head of the piston forces the whole thing to cycle open again.
One curious thing to note here, and I don't think it's of any particular functional significance,
is that the FG-42 here and the Korsac the bolts rotate in opposite directions.
And you can see that from the mirror image cam tracks in them.
So ... let's see, they're both going to be open like this and
the FG-42 is going to rotate clockwise, the Korsac rotates counter-clockwise.
But that's about the biggest mechanical difference between these two.
Alright, now the Korsac is a bullpup, so we are going to have to change the design a little bit.
This can't just be a straight copy of the FG-42, and the reason is the trigger mechanism.
On the FG the trigger is basically right below the chamber,
and so the two sear locations can be located on the operating rod itself.
The bolt is sitting right here, and so the semi-auto sear can be right underneath the bolt and everything works nicely.
On a bullpup you have to have a way to transmit the trigger action back to the actual sear
which is going to be back in here somewhere.
The way they do that is with this interesting sliding block.
Now this is set up so that the gas piston fits in here, and it actually has a matching slot
so that the charging handle locks these two together.
(If I line them up correctly,)
So the charging handle locks the bolt to this sliding bar by way of the gas piston, and this is going to cycle all together.
Now on the bottom of this we have a sear notch at the front, and we have this sear notch at the bottom.
And those interact with the two sears in the trigger group.
This sliding bar is going to act as the sear catch, so in the ... full-auto mode right here,
you can see that the sear is hooking on the front of this bar.
When I pull the trigger that sear is going to drop and allows the bar past. If we switch to semi-auto mode
we have now lifted up this, the right hand semi- auto sear, which is going to catch in this track.
Of course that track allows the bolt to come
almost all the way closed, like this, before it drops and allows the
last bit of forward travel like that.
Now they did find in testing that in semi-auto this gun wouldn't reliably fire.
There just wasn't quite enough spring pressure left
in that little bit of forward travel to actually set off a primer.
Now it did work well in full-auto, because of course in full-auto you are starting way back here.
You've got a lot of time to build up the full momentum from the spring being fully compressed.
So it may have been partly that that led them to scrapping this project in favour
of what would become the other EM-1, and then the EM-2 rifle.
So the barrel assembly here has a set of Bren style locking interrupted threads on the back, which we can see there.
And then you can see that there are two angled surfaces cut, one here, and one here.
And those are the surfaces that are going to force the bolt to start rotating into its locked position
inside this area.
So these are going to match up with the locking lugs inside the receiver.
We have a gas block here at the midpoint of the barrel,
and that is actually going to run a short little tappet style piston. That's going to come back when the rifle fires,
and impact on the front of the op rod here to push that backwards.
It does appear to have been adjustable with two different positions. Although I don't know exactly what the two positions are.
Presumably two slightly different sized gas apertures.
And then in the front we have our folding front sight, a small conical flash hider, and bipod legs.
I have to say this is not one of the most confidence inspiring bipods I've ever seen.
Its legs are very close together, which wouldn't make it particularly stable.
The locking system in the field would be considered completely too flimsy.
But of course this is a prototype sort of gun,
and had it obviously gone into production they would have improved that.
It does also have a bayonet lug under here, interesting to note. So you could fit this with a bayonet.
Now if we consider production of this gun, ... one of the things that's going to occur to people with manufacturing backgrounds is,
"Holy cow, you have to cut interrupted threads for the barrel here, right smack in the middle of this long receiver.
And that is going to be ... basically an impossible job. To get a tool head
that's this long to come in here, and then accurately cut ... interrupted threads for the barrel."
However, if we look closely, we can see that there's a seam line right in front of the rear sight, right there.
So this was actually manufactured in two pieces.
You have the front half of the receiver here,
which is all just hollow tube basically, pretty easy to to drill out.
And then you had a somewhat more complex piece back here,
but you could drill the small holes for the gas piston and the bolt assembly in the back,
and then you could drill out the big hole for the locking assembly in the front,
and then you would take a separately machined interrupted thread nut, basically, press it in here,
and then weld the front of the receiver on. And I'm pretty sure that's how this was manufactured.
They did a really good job of it though, and it's a nice, very small, clean little seam.
Well, there is in fact only one of these rifles in existence, and it's very cool to have been able to take a close look at this one.
I love looking at the the history of where these German World War Two designs ended up going.
And this is only one of several German mechanisms ... where the development was continued by the British
after World War Two leading to other newer and cooler guns.
So I'd like to give a big thank you to the National Firearms Centre for allowing me to take a look
and pull apart this extraordinarily cool Korsac light machine gun.
Their collection is not open to the public, but it is available by appointment to small arms researchers,
so you can call them up and arrange to schedule a visit for yourself.
Or right now you can head over to Armament Research Service's website, take a look at their blog, the Hoplite,
and they will be posting close-up high-definition pictures of this rifle as the video goes up.
Thanks for watching.