Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and I'm here today at the Rock Island Auction Company
taking a look at some of the guns that they're going to be selling
in their upcoming April of 2018 Premier Auction.
Today we're actually not looking at a gun, we're looking at a light mortar.
This is a Japanese Type 10, what we would
colloquially call a "knee mortar". What's interesting about
this though is this is the early version of the device.
Not many of them actually saw combat in World War Two, and they
definitely weren't really being used to launch grenades by that point.
However, we'll start at the beginning. These were introduced in 1921.
This is called a Type 10 because that was the 10th year of Emperor Taishō .
And this was introduced to replace rifle grenades.
The Japanese were aware of World War One and they learned some important tactical lessons from it,
despite them not being a major participant.
And one of those was that the new combined arms tactics that really came out of World War One
required a way for the infantry to be able to throw explosive projectiles
... less distance then say a crew-served mortar, but farther than you could actually throw a hand grenade.
Now a lot of the combatant nations in World War One did this with rifle grenades.
And in fact the French, for example, would continue to use rifle grenades for decades to come.
The Japanese decided that they didn't really want to be using rifle grenades. They wanted a dedicated,
well, light mortar or grenade projector. That would be the ... appropriate term in Japanese, it's a grenade projector.
And so they came up with what we call the knee mortar.
Now this early version, this Type 10, weighs in at a whopping 5.5 pounds, that's 2.5 kilos. It is very light.
It actually disassembles into a very small convenient package for easy carry, which is pretty cool.
And it's effective out to a maximum range of about 250 metres, adjustable all the way down to about 60 metres.
And there are just a lot of cool little elements that go into this, so let's take a closer look.
I'm sorry, I seem to have disassembled it. This is the Type 10 in its transport mode.
And just for a size comparison, there's a Type 14 Nambu pistol. This thing is really remarkably compact.
What they did here is really both fairly simple and clever.
The base plate comes off, that's just held in place by a little spring-loaded detent, right there.
And then the handle, the stock of the thing just flips around and threads into the barrel.
Unscrew that, this whole assembly comes out.
That is why ... you might have noticed earlier, that the inside of the muzzle is threaded.
That is for this cap.
And then we can just flip it around,
thread this on, it has a little detent that will catch right there.
And then you just pop the base plate on,
and the unit's ready to go.
Now the grenade that this threw was about 1.16 pounds, which is right about half a kilo.
It was a pretty wimpy light grenade, didn't have a whole lot of impact. Which is part of why they upgraded this thing.
We'll talk about that in a moment. But one element to it was that, if I can find it here, there we go,
there is a big ol' vent hole in the bottom of the firing chamber. And that was used to control range.
So as you open and close this vent hole, you are
increasing and decreasing the amount of pressure actually acting on the grenade,
and thus adjusting its range.
And the way that was done in practice is with this convenient little scale.
Zoom in on it so you can see it. Note that there is an arrow right here,
and there's an arrow right down in there. And then we have a scale
right in here that is going to start at 6, which I'm pretty sure is 60 metres,
and runs up to 10, 15 and 20, sorry, 25. So right about there is our maximum range.
And then there is a second scale, right up here, that runs from basically about 5 again up to 20.
So if I use this bottom scale I am ... fully opening and fully closing that vent port.
If I use the top scale, which would have been for a heavier projectile,
Unfortunately, I don't know exactly what the two different projectiles were intended to be for these scales.
But with this smaller scale that's the minimum range, which tells me that if you try and fire a heavy projectile
with the thing totally open, its gonna go about 5 yards and blow up and hurt you presumably.
So for that top scale you have that top arrow as an indicator.
So that scale gives you the range, and then you also have an aiming line that is cut into the side of the barrel.
So what you would do is position this at a 45 degree angle pointing downrange
... using this line as basically a sight to line up on whatever it is that you're trying to hit.
Set the range with this. And then in order to fire it you pull this lever.
Now normally there would be probably a leather lanyard tied to this.
Note that when using this you would do it like this.
So the sight line is going to be on the top of the barrel and it lines up with this trigger lanyard.
You have your range scale right here where you can see it.
The vent is on the opposite side so it's venting downward. So it's not in danger of actually hitting your arm.
And you would fire it like this.
Now I can take this apart to show you exactly how the firing pin works,
but in the process note that there is a little spring-loaded detent here.
And that is what prevents the barrel assembly from unscrewing when you don't want it to.
That plunger
snaps into that little hole and just prevents it from turning.
Conveniently, taking off the barrel allows me to show you the firing pin protrusion.
So when I pull this lever down, it's going to retract that, and then snap it up. That would fire your grenade.
So this isn't like a typical mortar where you drop the charge down and it hits a fixed firing pin.
On this, you would drop your projectile into the barrel and then aim,
and when you're ready to fire, you pull the lever and that actually fires it.
That's pretty much all there is to the mechanics of this thing. It was simple, it was compact.
I think I mentioned they had basically a leather skeletonised carry sling for the thing.
You would put the stock in the barrel, put the base plate around the edge of it.
And then the whole thing went into basically kind of like a leather
pair of caps each end and some leather straps in between, and you can sling the thing over your shoulder.
I guess the last thing to address would be the curved butt plate.
US soldiers tended to think of that as something that meant it was supposed to go over the top of your leg for firing.
That's a dumb idea, it will hurt you. In reality this was so that you could
basically adapt this thing to any sort of ground condition that you found yourself on.
So, soft ground you could easily dig this in and hold it at a nice 45 degree angle.
If you had rocks, logs, any other sort of object on the ground, you could fire it off of those as well.
If you're interested in more of the tactics and the techniques used for these as grenade ... projectors,
definitely take a look at my other video on the Type 89, which explains that in a bit more depth.
Despite being technically adopted in 1921, these didn't actually go into production until 1923.
Takes some time to tool up for stuff. When they did it was at the Tokyo Army Arsenal.
And they weren't being made there very long before there was the giant earthquake in Tokyo,
which largely destroyed the Arsenal.
After that, the production facilities were moved to the Nagoya Arsenal, where these were manufactured.
About 11,000 of them total from 1925 until 1937, or thereabouts.
However, they would fall out of front-line service ... in the early 1930s.
So in 1929 the Japanese formally adopted the Type 89 grenade projector, which is kind of like this thing on steroids.
They improved the ranging system so you no longer had gas venting. They were a little heavier, a little stronger.
They had rifled barrels which was important, that made them more accurate.
They made a bunch of improvements to them. And the Type 89 became the primary
grenade launching weapon version of this device.
At that point the Type 10s here were relegated to basically signal and flare use.
So they were still usable tools, they continued to produce them for about 5 years while they were making Type 89s.
And they ... did actually use these in World War Two, but it wasn't really to throw explosives,
it was for flares, illumination flares or signalling.
If you would like to add one of these to your own collection, there are really very few of them out there.
This is, well this one's obviously seen better days, this was refinished a very long time ago.
But it is an intact and registered destructive device, fully functional as far as I can tell.
And it would definitely make a very cool addition to anyone's Japanese firearms collection.
So if you would like it, take a look at the description text below,
you'll find there a link to Rock Island's catalogue page
with their pictures, their description, their value estimate.
Everything you would need to know about this to confidently place a bid on it
through their website, or here live at the auction.
Thanks for watching.
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