Gear-Ratio-Accelerated? Yep, It’s a Thing: French MAT 1955 Prototype

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EDIT: Shoot, I managed to get the gear ratio backwards. Sorry! The recoil action provides the necessary delay, and then the gear ratio provides acceleration to ensure the bolt can open reliably, akin to the accelerator in a Browning M1917 or 1919 machine gun, or a Lahti L35 pistol. Please excuse the error…

In the search for an improvement to the MAS 1949 rifle for the French military, all the French arsenals proposed new designs. MAS supplied an updated version that was ultimately adopted as the MAS 49/56, but the Tulle Arsenal (MAT) had a wacky idea of its own. In 1955, they presented a short-recoil, tilting bolt, gear-ratio-delayed system. It was an open bolt firing rifle chambered for the 7.5x54mm cartridge, using detachable 20-round magazines. Today we have one of the first models to look at, and there was a second iteration in 1956, which lightened the rifle by replacing some steel parts with aluminum. Neither was successful, much the the relief of the French Army…

Many thanks to the IRCGN (Institut de Recherche Criminelle de la Gendarmerie Nationale) for allowing me access to film this unique rifle for you!

Full video on the St Etienne Mle 1907 heavy machine gun:
https://www.weaponsandwar.tv/videos/the-st-etienne-mle-1907-france-s-domestic-heavy-machine-gun

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[ MAT 1955 Rifle ] Hi guys, thanks for tuning in to another video on ForgottenWeapons.com. I’m Ian McCollum, and I am here today at the IRCGN, the central ballistics lab of the French Gendarmerie, taking a look at some of the really cool prototype French weapons that they have in their collection.

And today we have a MAT Model 1955 rifle. Now this stems from the time period when the French were looking to upgrade their MAS 49 rifles. And what they would eventually adopt would be the MAS 49/56, which we’re actually pretty familiar with in the United States

Because when they eventually surplused them when they became obsolete, a huge number of them came into the US and they are relatively common for us. But when they went to adopt that rifle, they did consider options other than just modernising the MAS 49.

And so the other two major arsenals in France at the time, Châtellerault and Tulle, both submitted designs. Now this was Tulle’s design. They initially prototyped it in 1954, and then the first trials version was the Model of 1955, which is this.

And it has a big handle on it which is very odd, but let me tell you what, it gets so much stranger inside. Let’s just dive right in and take a close look at this. All of the markings are right here on the side of the receiver,

Manufacture Nationale d’Armes de Tulle, so the Tulle Armoury, 1955 pattern. Now only a few years before this Tulle had developed the winner of the French submachine gun contest, which was adopted as the MAT (m-a-t) Tulle, the MAT Model 49.

And for this rifle they just copied the grip assembly as well as the grip safety from the MAT 49 submachine gun. So a very clear provenance to Tulle here. So if we look at the controls on it, the safety is just this grip safety.

Got a trigger there, this is for disassembly. This is actually for grenade launching. If we go out to the muzzle end of the rifle, you can see that there is a grenade spigot on it. This screw is set up to determine the range of the grenade

By determining how deep the grenade sits on the muzzle. The further down the grenade sits, the more time it is accelerated by muzzle blast when fired, and the further it goes. We have a grenade launcher sight here. This is … a rudimentary system where you actually have to unscrew it.

And then you can lift this up into either the intermediate position, or the fully vertical position there. And once you are using it like this, you line up this with the nose of the grenade to aim it.

This is a very similar style of sight to what you would get on the MAS 49/56. There is also by the way, [an indirect] fire grenade option, where you have a rear sight here and a little front sight right down there.

So … for [indirect] grenade [fire] you can aim like that. This feature I think, but I’m not sure, is an afterthought add-on to mount a bipod. It’s definitely not a bayonet mount, and it doesn’t have any functional addition to the gun, so I think that’s a bipod mount.

The front sight is a barleycorn post inside a nice big protective shield there. And the rear sight looks rather strange from the side. It’s got this sort of odd shield on it, but what it actually is is a … dial aperture.

So you’ve got your choice of apertures, you can’t quite see them, there’s actually five in there. And you pick whichever one you want lined up to use. This particular one is for 500 metres, you can see we have 600.

And if we roll it back on this side 400, and I think there’s a 300 and a 200 as well. Now the charging handle is obviously what really sticks out on this rifle. So you unlock it from its little latch here, and then – that’s how you cock the rifle.

And if we look at it on this side, this is an open bolt rifle, so it fires from the open bolt. I can’t fire it at the moment because it has a magazine in it, and it does lock open on an empty magazine as well.

Got a magazine release tab down here. We can pull this out, this was a proprietary magazine design, it holds 20 rounds. There’s your hold open tab, pretty simple stuff there. But you can now see that this fires from the open bolt.

So that’s cocked and ready to fire, that goes forward. Now unfortunately this example is missing its bolt. So what we have here is a barrel extension, a bolt carrier. And you can see the hook there, vaguely reminiscent of a Sturmgewehr or a FAL.

Normally we would see a bolt cycling in the front here. Let’s take it apart. Let me show you the weirdest part, which are gears inside the gun. So for disassembly we are going to unscrew this. It is not captive, it just comes right out.

That allows me to drop the back end here. With that down, I can use the handle to pull out the internal assembly. There’s a pin in there that’s coming loose, there we go. And now we can pull out everything. So we have barrel, barrel extension.

This pin that comes out. And freaking gears inside the gun. Next step in disassembly is to unscrew this pin. Once that comes out, then I can remove the lower assembly. There’s another part of our rack and pinion system.

And then we have a sheet metal upper, and there’s basically nothing going on in here. There are going to be two recoil springs in this gun, because it is a recoil operated gun. So you need one spring on the barrel because the barrel

Is going to reciprocate with every shot, I’ll show you that in a moment. The return spring for the barrel you can see right through these holes. And let me take a moment right now … to point out this lever once again. This is in the regular fire position.

And if we look … right up in here you can see a lug. And as I rotate this lever, that lug is going to lift up and drop down. So when that lug lifts up … it is actually locking the barrel in place right here.

And that’s for grenade launching. So because the barrel moves back when firing, If it was allowed to move when you fired a rifle grenade, it would have a lot more force going backward than it’s intended to. So when you fire rifle grenades you lock it in this position. The rifle will not cycle.

And so you have to manually cycle each round through. This is the equivalent of a gas cut off on a gas-operated gun. This is … we could call it a recoil cut off because it is a recoil-operated gun. So that’s what that does.

Now let’s get back to this nightmare. What we have here is a centre gear here. … As the bolt carrier runs back and forth it’s going to turn this gear. So I can use this gear to actually move the bolt carrier.

And then you’ll notice that there is a large diameter set of teeth here, and two small diameter sets on the outside. Those small diameter teeth interface with this [rack] on the lower assembly. So I can take this pin out, remove the gear.

Note kind of cool, they actually have a block here that works in conjunction with this space right there. So this is how you time the gear, because if you set it in the wrong position it won’t fit.

You set that there, and now you know that the system is properly timed. Again, we would have normally a bolt sitting in here. So the way this would normally function, when everything is in battery, so this all the way forward,

The bolt would lock into that recess in the top of the barrel extension. So that goes forward, it’s all locked together. This is typical of a recoil-based system. We’ve got the barrel locked into the bolt face.

Think of this as a Browning-style pistol where the barrel is locked into the top of the slide. Well, this is effectively your slide, this is effectively your bolt carrier. Now when you fire, recoil is going to push this entire assembly backwards.

And … when that happens these two interior teeth start rolling on this. The whole assembly is going to move backward just like the slide of your pistol. Now because of the difference in the diameter of the inner and outer rings on the gear,

These are going to move a lot faster than these are. So what that means is that the action of pulling the bolt back here is delayed compared to the action of this moving backward. So if this moves backward an inch, let’s say,

The bolt is going to move backward much less than an inch. I don’t know the exact ratio, but a third of an inch or quarter inch or a half inch. Now there some delay time also built into the bolt itself, which we can’t see because the bolt is missing.

But as this component starts to move backward the bolt is going to do nothing for a moment. And then it’s going to unlock, it’s going to drop out of that locking recess. And because of the gear reduction here,

By the time that actually happens pressure will have dropped to a safe level. Now while this is happening, this recoil spring is compressing against the back of the action here, and it’s a really strong spring. I can’t really effectively push it back and compress it to show you.

And that is why there is this big lever. You need this lever to get enough … leverage to be able to compress this recoil spring to cock the action. So this makes sense. … You could call this a recoil operated …

It’s not a delayed blowback, because this is a locked system, but it uses a gear reduction mechanism to give it a delay in opening. So instead of a tilting-barrel short-recoil system, we could call this a gear ratio … short-recoil system.

Now you saw that it fires from an open bolt. And the firing mechanism itself uses this notch right here as essentially your sear. So this is your firing component. This hook, right there, locks into that recess right there.

And when I pull the trigger, it’s a little hard to see here out of the gun, but this … finger just drops very slightly. That releases this against spring pressure, slams forward, fires automatically when it closes. And cycles. This little tab right here is our disconnector.

So when I push that in, it’s going to reset this because we have it in semi-auto right now. This is a select fire rifle, so it’s semi-auto in front. The back is actually labelled “M”. There it is, the marking is on the outer … receiver shell.

There’s “M”, that’s mécanique, that’s full-auto and the forward position. The marking itself right there, is on the outer shell. And there sort of is a marking there, not really. Rearward “M” is full-auto, forward is semi-auto. This is actually, surprisingly, not the first French gun

That I’ve looked at that actually had a rack and pinion inside it. The other one that comes to mind is the Saint-Étienne Model of 1907 heavy machine gun, which used a rack and pinion essentially to turn a rearward … operating piston

Into a forward operating piston to avoid paying royalty fees. That gun was France’s standard heavy machine gun going into World War One, but was very expensive to produce. Ironically it was more expensive to produce than just paying the royalty fees

And buying Hotchkiss guns, which is what the French military started doing as the war really continued. But apparently someone at Tulle took a look at that gun and thought, “That is definitely what we ought to be working with, let’s try that again.”

And hence we get the MAT Model of 55 and Model of 56 rifles. Now when this rifle actually got to trials it didn’t do very well. And that probably isn’t going to surprise you having seen the inside of it now.

But specifically the report was it was fairly fragile, it broke more than it should. Weird for a gun full of gears. And it also had pretty poor accuracy. They surmised it might have actually had the wrong rifling twist in the barrel. I’m not clear on the exact details, but.

There was a subsequent version that was made in 1956 where they attempted to improve the design. They made it a bit lighter by replacing some of the parts with aluminium. It went back to trials, it still had substantial problems.

Again no surprise: guns with gears in them? Just not a good idea. And so this went no further than the 1956 trials. And of course at that point the MAS 49/56 was adopted as France’s new standard infantry rifle.

So very, very cool to get a chance to take a look at one of these trials rifles. Like, gears in guns are a terribly bad idea, but they are so cool to look at. So hopefully you guys enjoyed the video.

A big thanks to the Gendarmerie for giving me access to film this one for you. Thanks for watching.