Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and as you may be able to tell
I'm in Finland right now taking a look at some
really cool historical Finnish firearms.
One of which we have right here,
this is a bunker model of Suomi submachine gun,
or a "Korsu" model,
which I'm mostly pronouncing correctly I think.
And this was developed for a very specific need
that the Finns discovered basically in the summer of 1939.
It was becoming obvious that there was a potential conflict coming with Russia
on the southern end of the Finnish-Russian border.
And so the Finns started building a series of fortifications, including a lot of bunkers.
And in the summer of 1939 one of the Generals associated with this bunker construction
discovers that there is a bit of a problem.
Namely, the primary automatic weapon available to the Finnish infantry,
the Suomi m/31 submachine gun, well the muzzle on this thing
is a little bit too big to fit through
the very narrow vision ports on all the bunkers they're building.
You don't want to make the vision ports bigger because of course
then you run the risk of ... more enemy fire coming in.
But it's really hard to shoot out of the bunkers with standard submachine guns.
So for one thing they have long stocks, bunkers are by necessity small.
The vision slit is narrow enough that, first, you can't see the sights
(this is like the extreme version of a VTAC barricade almost),
so you can't aim the thing at all.
And even ... if you accept that,
the slot is narrower than the muzzle of the gun.
And so the gun has to be actually inside the bunker, and aligned just correctly.
And at the rather high rate of fire of the Suomi
you run a very real risk of recoil pulling the gun back, and then climbing a little bit.
And now you're shooting the bunker wall on the inside
an inch past the muzzle, and that's a real problem.
Even if you keep the gun properly situated,
you've got a lot of smoke and flash that's coming back into the bunker.
It wasn't a good situation, and so what they decided to do,
and they operated on this rather quickly,
by September of 1939 they had a concept in mind of this.
Let's create a different barrel jacket that has a constricted ... barrel jacket at the muzzle
(it almost looks like a duckbill style of shotgun choke),
that's narrow enough that it can go through the vision slit in a bunker.
And this will provide a number of benefits.
One is a safety benefit, we can make sure that all the bullets actually go out.
Second is the smoke and the flash can be directed out.
And we can set it up with some sights that you can actually use.
And what's really interesting to me is you will occasionally see pictures of these in books, but
... for some reason no one ever really highlights the sights.
Because there are actually sights on this, they're on the side here, let me show you.
I should of course point out that in addition to the different barrel shroud and sights,
there was also a substantial change made to the receiver and the buttstock.
The regular m/31 Suomi has a nice heavy wooden stock, obviously.
And what they opted to do for the bunker model was basically cut this stock off right about there,
and then reshape the tangs (upper and lower) to form ... just a single vertical pistol grip.
The idea being in the bunker you're supporting the gun on the muzzle,
you don't need the stock quite so much. And of course there's very limited space.
And so it's a lot easier to move the gun around inside if you don't have a stock hanging off of it.
So you can see the original tang there,
which has been screwed to this reinforcing bar for the rear pistol grip.
And then the bottom tang was actually cut off, and then this added on.
And that gives you a two-part wooden pistol grip.
Now the sights: mounted on the side, properly gangster style.
Unadjustable open-notch sights.
Of course this is not supposed to be a long-range precision sort of weapon,
this is for clearing enemy soldiers off of the bunker.
So there's your rear notch,
and a front post on the side.
And that is sufficient to give you a usable sight picture
through one of these very narrow vision slits.
In terms of the rest of construction, the basic receiver,
other than the slight modifications for the pistol grip, is identical to the standard gun.
These would take all of the normal magazines.
The 71 round drum introduced in 1936 is probably the most common.
Certainly ... you don't have to deal with the weight of carrying it around,
and it's got the most ammunition, so I'm sure it would be the preferable magazine for use in a bunker.
The ... fire control group, the bolt, everything else is identical.
And this is where one of the neat elements of the Suomi really came in handy,
that being the interchangeable barrel which ... is coupled with an interchangeable ... barrel shroud.
So what you do is simply unlock this lever, and then the barrel shroud can rotate off.
This one's stuck in place, so we'll just leave it there.
But you can take the shroud off,
and you could replace it and the barrel with standard components very easily.
And ... what that means in production is that you can essentially manufacture a standard gun
(you can see they even left the top sight on it because
it's more work to make a special run and take the sights off, than to just
put them on there and then ignore them when you don't need them),
and just put on a long barrel and a long shroud.
There were, by the way, initially two lengths of this that were tested
(there was basically a 15 inch and a 17 inch) in the fall of '39.
They opted to go for the longer barrel,
because it reduced the amount of flash from the cartridge.
Which isn't a big deal for the infantry,
but it is more substantial for guys inside a dark, tightly-enclosed bunker.
If we look at both of the muzzles here side by side,
you can see that the bunker model is about half the height of the standard submachine gun.
And it's got that nice taper to it so that you can wedge it nicely into the viewing port.
So the first batch of fortification Suomis was manufactured before the war, in the fall of 1939.
There were 500 of them, and this original batch runs from serial numbers about 5,900 through 6,400.
That was a start.
In January of 1941, after the Winter War but before the Continuation War,
another batch was manufactured.
They made 10,000 Suomi machine guns overall, 500 of those being bunker models like this.
And those ... are not a single continuous range,
they'll fall in like the 13,000 to 17,000 serial number range.
These were kept in Finnish ... military reserves into the 1970s,
when they were ultimately disposed of.
But ... if you're going to have fortifications, it's nice to have kind of a dedicated weapon
that's well suited to using from within them.
So they are of course really quite rare today,
and it was very cool to get a chance to take a look at this one.
Hopefully you guys enjoyed the video.
Thanks for watching.