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SIG AK-53: A Truly Weird Forward-Operating Rifle


Hi guys, thanks for tuning in to another
video on ForgottenWeapons.com. I’m Ian McCollum, and I’m here today at the National
Firearms Centre, part of the British Royal Armouries in Leeds, we’re taking a look at a Swiss AK-53. This is a prototype rifle that saw no commercial
success for reasons that will become incredibly clear to you in the next
couple of minutes, or a couple of hours depending on how long it takes me to actually
describe how this nutty thing works. This is gas-operated blow-forward.
Although it’s not blow-forward, that suggests that it’s unlocked,
it is a locked breech gas piston (an annular gas piston), that causes
the … barrel … to actually recoil forward. Let me just show you. When you cycle the gun the bolt
… (I keep saying bolt), the barrel goes forward, like that. These were chambered in two different cartridges.
They were made in 7.5x55mm Swiss and they were also made in the T65 cartridge,
which was that, like, pre-7.62 NATO calibre. They saw absolutely no commercial
success, very few were made. This is serial number 156, although I don’t know if
that is a total number of these that were produced, or if, I suspect, that is a sequential number from a
bunch of different types of post-war experimental rifles. So, without further ado, let’s go ahead and start
digging into the mechanics on this because there’s really no other history for me to tell you. They
experimented with it, and it went nowhere. So let’s dig in. Alright, we are going to start by taking out the
magazine, because this is a huge magazine that kind of gets in the way for me to
be able to show you the rest of the gun. So this lever up here is actually the magazine
release, and I have to pull it all the way down, like that, and then I can pull the
magazine out. Now, let’s take a look at this. So this started out life as an LMG 25 magazine.
… It should be 25 rounds I believe as a result. However, they had to seriously change up the design
at the top in order to accommodate this thing’s strange blow-forward or forward
acting gas operating system. And (I’m gonna get this out of the way, so
it doesn’t try and keep focusing on it), basically what we … need is to be able to have
a cartridge go straight up from the magazine into the breech face. It doesn’t
push forward, it just goes straight up. Which means, well, at the same time you can’t
have rounds coming straight up out of the magazine when the magazine’s out, or else all the ammo
flies out of the mag and you have nothing. So they have these two feed lips that you can see here,
that are going to hold the stack of cartridges in. And then when you put this into the
gun, when you lock the magazine in, these two feed lips get spread apart and they
allow the cartridges to start cycling up one at a time. So when the [barrel’s] closed that’s going
to hold the stack of cartridges in place, when the … barrel opens, goes forward, it’s gonna
allow one cartridge to come up high enough that when the barrel cycles back, it locks over
that cartridge into the chamber and is ready to fire. So, you can see there are two
little square lugs on the side here. If we look inside the magazine well,
when I close the magazine lever here, when I open that this opens up and you
can put the mag in, and when I close it these two arms come back and
what those are going to do is actually squeeze themselves in between the magazine body… In between the body here, and these two arms,
so they’re going to pry those arms out. These lugs are going to lock into the side of the
receiver, right here, to hold the mag in place. And when the feed lips are spread far enough
apart the cartridges will pop out the top. So that’s why this is a really stiff… you know that these levers are nice and
easy to operate without a magazine, but when you put a magazine in (and by the way
there is also a front lug here that locks this thing in to get it at the correct height), when
we put this in right to that position, and then close the magazine lever, it’s now really
tight because it has to pry these two up away from the magazine body. By the way, the
one major publication that talks about this gun, The World’s Assault Rifles, says that
this is a disassembly lever, which it very much is not, there is no
disassembly lever. So let’s move on to… Well, actually a couple markings I should show you. … This is really the only marking on the gun, the only
descriptive marking, 156. That’s the serial number. All right. Now we have a bit of a conundrum back here.
We have two selector markings ‘E’ and ‘M’ and I’m not sure what those are supposed to stand for. I’m used to like ‘E’ and ‘D’, or ‘S’ and ‘F’, or ‘E’ and ‘F’.
Red usually means fire, white usually means safe. We also have the situation here of something
that’s fairly typical of Swiss firearms, namely you have this ring shaped
cocking piece and so, in theory, that ought to be the safe position
with it horizontal, but it’ll fire there. Because you can also take this and
rotate it 90 degrees, again, typically Swiss, but it’ll fire there as well. So I’m not sure what… And all configurations of this will do that. So, I’m not sure exactly what the firing
controls are supposed to be here. What I do know is, according to the literature, this has a cyclic rate in full-auto of 350 rounds per
minute, which … I do find plausible after taking it apart. We’ll get to that in, I promise, just a moment. But how exactly these are set up,
I don’t know. This has to be a select-fire gun, there’s no way that a rifle like this would be
full-auto only, but it clearly is capable of full-auto. So if you know, tell me down in the comments. Moving along, we have a rear sight
marked out to 1,000 metres. This is, very curiously, very similar to actually
the MAS-36 and the early MAS semi-auto rifle’s rear sights, where you actually have to push
down (it’s an aperture sight back here), and you have to push down on this and then you
can adjust this slider to whatever range you like, and then let the … actual leaf up
(so push that down, slide this). The French got rid of this on their rifles,
because they found that when you were shooting, under recoil this would tend to
bounce and the sight would shift. So they went to a different system
where there’s a locking button on this slider. Why you have that French sort of
influence on this guy? I don’t know. Our charging handle is right here on the side. And, of course, despite the fact that I keep attempting
to pull this backwards, you do in fact cycle it forwards. And when you do, the barrel extends out the front
of the barrel jacket, and past the muzzle brake. Notice the two big oval slots in the barrel there,
those are to line up with the muzzle brake. So you get some effect from
the muzzle brake through that. I do also want to point out that on this rifle it
should be re-cocking whenever you cycle the action, but it doesn’t. And whether that’s related to my inability
to figure out the safe and fire positions I don’t know. But we’ll document exactly what we
have here, and that’s what’s going on. The muzzle brake is just three slots on either side. We have a fairly typically Swiss front sight, although it’s
not protected with wings, which is a little bit unusual. We have a bayonet lug on the bottom, sling swivel on the side of the barrel jacket, and then a sling bar in the back, along
with a somewhat unusual style of butt-stock. That’s in there to allow you to get a line of recoil
a little bit more closely to direct into your shoulder, instead of having your face and your
line of fire elevated up above the shoulder. So it’s actually not that
uncomfortable of a gun to handle, although it is a bit front heavy with
all the weight of the jacket and such. OK, now we can get to disassembly. And we are going
to start by removing the front cap on this barrel jacket. There’s a little wire here, which sits in a detent, right there, on this front
component. Just that prevents it from rotating under recoil, but it’s nice and easy to
pop it loose to take it out. So this unscrews. There is a big spring behind
this, so once we get it a little bit further out we will have to hold onto it carefully,
lest it go flying across the room. There it is, it tried to go flying
across the room. Alright, so we have a couple of
different things going on out here. This is the part that was actually
screwed into the front of the barrel jacket. This is our gas piston. This guy is one of two springs in this system. This would be, we’ll call this the gas piston spring as
opposed to the barrel spring. So this, by the way, is reminiscent of the MG42, this is a two wire,
yeah, that is a two wire coiled mainspring. Now, without that spring, this barrel assembly
is free to reciprocate back and forth here. This is all going to come out the back of the action, so the next thing we need to do is
take out this cocking piece section. This is a little bit fiddly to do.
I don’t have a manual for this, we just kind of figured it out by trial and error. So, we have a locking bar right here, and this will rotate through … 90 degrees, what we need to do is actually get it in a position where it will come out. There we go. So that comes out, and then, as I’m pulling this back, it is
actually linked to the barrel assembly by this. So, does this not look incredibly Swiss, or what? As I pull this out it’s going to come to here, should be able to go a little bit farther… [several minutes later] Quick intermission, we’re gonna go ahead and take the
charging handle off, because I think it’s catching on the bolt. So, what we do for that is lift up on this little lever, which is holding in a lug that holds this whole
thing on. Then this handle can slide off the front. By the way, I forgot to mention it, this little
button is your manual bolt [barrel] hold-open. If you push the handle forward and then push this down, it’ll lock the bolt [barrel] open, which makes
things like magazine changes a bit simpler. There we go, all right bolt handle is off. You can see
the little lug, right there, that was holding it in place. Now I think… There we go. Now we can pull this the rest of the
way out. So this is our whole cocking piece assembly. (Just a little bit of persuasion),
that is the barrel assembly, our connecting bar,
and let’s call this the barrel spring. Now, before we go forward, I want
to point out a couple things. Right down in here you can see that
there’s not really anything going on inside this, the … barrel shroud here, except about halfway
down. You can see a black ring and that is a shelf, a step basically. And one of the springs is going to
sit on that step, so it’s important to remember that. Here you have the view down from the
back. There’s not a lot you can see here except on the bottom, right about there, you
can see sort of a semi-circular crescent shape. That is one of the two locking recesses, and there’s another one at the top that you can just sort of barely see there. But the top locking recess is … inside
this bulge at the front of the receiver. So the way this thing actually
locks is with two flaps, right here. These are oriented vertically,
when … it’s installed in the gun, and when this sliding piece goes
backward it forces those two flaps to lift out, and those lock into those two recesses in the
receiver, one in the top and one in the bottom. Looking at the face of the barrel here, we have, basically, just a big feed ramp
and an open area to allow the breech face in. This is our breech face and striker
assembly, and it’s fixed in the gun. So when I was taking it out, I’m basically
taking these interrupted lugs and arranging for them to pop out
the back of the receiver. The front here is our breech face. So
think of this as the bolt, except on this gun, because it’s a forward operating gun, the bolt
stays where it is and the barrel moves. The magazine is going to fit right here
into the bottom of the breech face. So when a cartridge feeds, it’s going to go
from the magazine and travel straight up into the extractor grooves right here. After you fire, it’s going to … be ejected out this side of the gun, and in order to allow that to happen we have a removable chunk of the … rim engagement,
so you can see that that’s got a little hook in it, a little cut in it, and that engages the rim and
holds the cartridge in place when you’re firing. Once you’re done firing, when the barrel starts
to go forward, this is going to be lifted off, which allows the cartridge to
tip out towards the camera. You can see that there’s a little cutout here that allows
it to lift completely out of the breech face and eject. In full-auto it’s fired by this trip right here. When this goes down it releases
the striker, it expands that spring and it comes up through the breech
face right there and fires. This, right here is, of course,
directly connected to the ring handle. So when I pull that back you can
see I’ve re-cocked the action like that. Dropping this guy, drops it forward and it fires. OK, so here’s the most complicated
part of the whole thing. And bear with me I’m … gonna do my
best to explain this. We have two springs, we have gas ports in the barrel here.
When this is assembled, you’ve got this gas piston spring sitting over the
top of this barrel spring. You remember how at the beginning I
pointed out a shelf inside the barrel sleeve? Well, that shelf is what this spring rests on. So when this is assembled, this gas piston spring is
acting against a fixed surface here in the barrel shroud. The piston itself is going to sit
right up against this ring, which allows it to compress
the … inner barrel spring. So, when you fire, you have your gas ports
… right here, which are going to vent gas into a chamber area in between this (which is threaded
into the very front of the barrel shroud), and this gas piston. So it’s it’s gonna fill this area with gas,
which is going to force the gas piston back. The barrel cannot move at this point
because it’s locked in place into the receiver. So, what’s going to happen is this piston is going to reciprocate
all the way back to here, and it’s going to lock onto the
front of the barrel over piece, thing. We’ll call this the ‘thing’ inside there.
The gas piston locks onto the ‘thing’, once this happens, we’ve compressed
the outer spring as well, and…. locked together now, this is all one component. And so as soon as this locks backwards,
gas pressure dissipates out, and then this spring is going to
push this whole assembly forward. And that is what actually pulls
the chamber off of the cartridge. So the cartridge is going to be sitting in the breech
face (actually, we’ve got our breech face right here), the cartridge is going to be sitting
in the front of this breech face, static. The barrel, under spring pressure,
is now going to move forward like this. So there’s a bit of a delay here, and that’s
what contributes to the low rate of fire. This piston has to compress back first.
This actually has shades of the Farquhar-Hill and the Beardmore-Farquhar British guns to it, sort of, not quite
identical, but elements of that. So this is going to go forward,
and it’s going to go forward until… So it’s here, and it’s going to move
forward like this, until this piece actually … until this slides up over this muzzle brake section,
because when this goes all the way in it’s going to trip this spring and unlock it,
plink, like that. At that point remember, this is threaded into the front
of the barrel shroud and static in place. So once we … release this inner spring, it’s
going to push the barrel backwards like that, which pushes the chamber back over the next
cartridge coming up out of the magazine, it re-cocks the striker in theory, but that piece appears to
be missing here. And then you’re ready to fire another shot. What I didn’t show you before that will make this clear. The way that this latching and unlatching
works is that we actually have this compression (I don’t even know what off
the top of my head because I’m a little bit befuddled from trying
to figure out this whole thing). I can’t remember what the technical name for
this is, but the four prongs on this will compress. And that’s exactly what the gas piston
does. When it goes all the way in, it’s actually going to latch over this, like that, and lock it in place. There’s a
little ridge right up in here that does it. And then this guy is going to push those four
tongues back down, which unlocks them from this, and allows this spring to expand again. Now we also have this connecting rod
to talk about. This is going to sit right in the side of the barrel assembly. So this is fixed
to the barrel, and as the barrel goes back and forth, this does as well. It has this little spring-loaded hook
on it, and this is what actually cocks the action. So I think I had this mis-
installed the first time, when you saw the outside of the gun, and we’ll find out when I
reassemble it after this whether it works properly. But the way this is supposed to work, this lug right here is connected directly to our striker. This hook, right here, hooks on to that shelf, right there. Which should then cock the striker
when this piece moves backwards, because this whole block is fixed in the receiver.
So that should make the whole thing work, and I suspect I previously had it installed
with the hook like just in front of that catch surface, or or something like that. So, that
I think is actually pretty much the whole gun here. I think that’s most of what we need to talk about. So you have two sear surfaces. You’ve got one down
here, and in semi-auto this is … what fires the gun. … The trigger drops this here, just like a submachine
gun sear, which would be holding this back. And then this is your out of battery
safety as well as being your auto-sear. So, the striker will be … re-cocked by
this guy, and then when this drops it allows the striker to come forward
(it’s already in the forward position). So, alright, let’s put this back together
and see if that actually works now. Alright, there is the SIG AK-53 field stripped. We’ve left a couple components together. Like
there’s no way I’m going to take all the pins out of this. I definitely don’t really want to get into
disassembling that. This took several hours to figure out to this point, and I think
we can pretty well understand how it works. So I’m going to now go ahead and
reassemble it, and see if it actually … speaking of which, see if it actually does
properly work once I reassemble it the right way. Alright, I have gotten it back together. However, despite my
best efforts to make sure I had it exactly put together right, it still doesn’t want to cock. So I don’t know why at this point,
and I am going to assume that either … well, I don’t have enough time here at the
Armouries to take more time to try and figure that out. And to be honest, I don’t remember if it
actually cocked before I started taking it apart, so it wasn’t something that I had noticed. So, … the good news is I did get it back together. So, in the recovery period after finally getting this
thing both disassembled and then reassembled, preparatory to putting it on camera here, I
was trying to figure out, like, is this actually the most complex gun that I’ve ever
disassembled. And the answer is not quite. Because for all of its ludicrous weirdness,
it actually comes apart with no tools. The trouble is understanding how it works,
because once you understand it, it’s actually not that complicated to
take apart. It’s just tricky to figure out, and there are other guns out there,
like notably the British EM1 bullpup that even once you understand how it works, it’s still kind of fairly tricky to actually
take apart and put together. So this is definitely … I think this is the
only forward operating gas piston … it’s the only forward operating
barrel moving gun that I’m aware of. So there are a couple other guns
that do have forward moving pistons. The Saint Etienne 1907 machine guns do,
but they have a fixed barrel and a gas piston that moves forward just so
that a rack and pinion can push a bolt backward. This has a fixed breech block and
the barrel actually cycles forward, sort of under the influence of a gas system. So I
think I can safely call it a unique operating system. But once you understand it, not actually
the most complicated thing ever. At any rate, I would like to give a
big thanks to the patrons out there, those of you who directly support
Forgotten Weapons and it’s you guys that make it possible for me to travel to find awesome,
totally unique guns like this one and bring them to you. And, of course, I found this at the Pattern
Room at the British Royal Armouries, and I’d like to give a big thanks to them as
well for giving me access to come in and figure out how to tear this thing down
and show it to you guys. So their collection is not open generally to the
public, but it is available by appointment to serious researchers. So if that describes you,
take a look at their link to their catalogue below. You can, everyone in fact can, check out all
of the different stuff they have in the collection. And if you’d like to make an appointment
to come take a look at something for your own research, ring them
up and they’ll work with you. Thanks for watching.

100 thoughts on “SIG AK-53: A Truly Weird Forward-Operating Rifle

  1. I mean a magazine release technically disassemble the magazine from the rifle so wouldn't it kind of be a disassembly lever

  2. E standing for Einzelschuss or Einzellader, transalated like Singleshot or Singleloading. Used for precice shooting.

    M stands fur "Mehrfachschuss" or "Mehrlader", translated to Multifire Multiloading(autoloading). Used for sturmabwehrschiessen, stormdefensefire or Close combat.

  3. My limited german and limited zwiss knollage tells me E is single as E for enkel which means single and M should be full auto

  4. Just a guess let me know if im right but e is for safe and it cams the fire pin stopper. Up and side ways on the ring is mode selection.

  5. The E could stand for “Einzelfeuer” means “single shot” and the M could stand for “Maschienenfeuer” means seriel fire – that would explain why its not safe in either poitions – but i don’t know…

  6. This is an absolutely horrible design. If anyone wanted to invade the Swiss, the best way would be to notify them of your intentions 6 months in advance and let them go to work on their weapons. At the end of 6 months, the whole country will be busy reading blueprints trying to figure out how their gun needs to be assembled.

  7. 19:20 HAHA! We have a special word for stuff like that in Russia! 😀
    ЦАНГА!!! 😀 It pronounced like TSANGA. 🙂
    And means ROUNDED SHRINKED CYLINDER PEACE THAT SHOULD WIDE OUT AND LOCK SOMETHING WHEN DECOMPRESSED. Like Blaser R8 locking of the bolt! :3

  8. 5:45 since it clearly doesn't work as a safety you think it might possibly be a fire mode selector? I know that doesn't explain it being colored white and red but…. maybe? Lol

  9. Minute 5:51, recalling Denio below, markings E & M, try "Einzel" for single [shot] and "Mehrfach" for multiple or "Maschine" for machine [gun], aka serial shot, "full auto". Minute 7:15, why French influence? 40% of the Swiss territory speaks French (Romand) and France had a big sympathy in Switzerland since 1833-48, and then again in the Franco-Prussian war (check "Bourbaki Panorama"), and of course after WWII.

  10. Soldier 76 from overwatch has a rifle that has a barrel which extends forward when your fire. I didn't know such a gun actually existed, I thought that was just a weird artistic choice.

  11. Oh my word! This thing is an engineers pub dare. "Bet you can't design an automatic rifle that works backward." On the other hand it proves anything can be done given enough time and machining. I wold like to see this rifle fire! Great video.

  12. The World's Industrial Nations all worked on auto-rifles during/after WWII- so the Swiss thought it was a good idea to do something completely different. Well- at least they left out the Luger toggle and the Geneva wheel.

  13. Another fascinating video. You've shown many guns that I have only seen in photos or drawings -the German belt buckle pistol I've saw in the early seventies and you actually showed a real one when I thought it was a myth.

    I live in Leeds and I hope you enjoyed a pint in one of the historic pubs in the city centre across the bridge. If they had let me or any other Brit near their guns we would be on a Scotland Yard and MI5 list. Meanwhile I'll have to keep watching your videos as the nearest I'll get to guns.

  14. Im no expert, but i think you have to release the barrel from its fully extended position rather than allow it to return gently for it to re-cock itself

  15. So why wasn't it a commercial success? Throughout the 25 minute video you never touched on this. To me it looks like a well built and reliable system, albeit extremely unconventional

  16. Why did we climb Mt Everest? Why did we put a man on the moon? Why did we build a rifle that even Ian couldn’t figure out? Not because the things are easy, but because they are hard!

  17. Ian working the action and the barrel poking forward out of the gas piston shroud made me feel extremely bad and unpleasant. This gun is a bad idea on a very visceral level

  18. Wish Ian had commented on why they would have constructed the gun this way in the first place. Would having the barrel go forward like this cut the recoil?

  19. looks like a clockmaker and gunsmith got together and this was the bastard offspring of the mating , WEIIRD is an understatement , still very interesting, thanks Ian

  20. How does a US citizen manage to get to such unique specimens of the Swiss arms industry and history in order to present them to us?
    Unbelievable what treasures this man has access to!
    As a former Swiss tanker soldier,
    with a very long family military tradition, I have been following this channel for quite some time with great interest and joy! Keep on making such brilliant and instructive videos, thank you!

  21. Light behind the camera would be a good suggestion when trying to show up close shots of these wacky pieces. They say there's a thin line between genius and insanity–pretty obvious which side this weapon ended up on

  22. "Must we do a field strip for cleaning after an engagement ?"
    "As any other gun,yes."
    " Ah,hmmm.It would be wise to become a neutral nation !"

  23. E means EINZELSCHUSS, single shoot,semiauto, M=Mehrschuss, Automatic fire. btw, in swiss eeryone has to go to the military when you are 18, still today, and after this you go home with your AR,still today also, so they needed a lot of rifle and this model was to overpriced and conplicated to handle! after the AR 57 SIG begins working with Beretta which endet with the new SIG 550 and the Beretta AR70/90, one of the best AR i have ever shoot

  24. Probably a clockmaker high on schnapps and every possible other Swiss herb went awire …after eating magic mushrooms…

  25. I want to see the behind scenes "off record" footage of this one….I can hear Ian saying something about a swiss cock ring , and the Barrell emerging from it's fore shroud.

  26. So Swiss engineers and machinists made that meticulously crafted barrel….then handed it over to somebody’s grandpa to widdle the stock in his rocking chair.

  27. The safety mechanism could be broken, or it could have just not been finished by this stage in testing. But either way, E and M is strange on its own. Normally german speaking countries label their guns with S for safe, but semi is E and full is F. I think E is normally "fire" on a normal firearm. Esepcially since it doesnt cock itself, its probably all broken to hell lol

  28. Maybe that back cocking ring is the selector? I mean, it fires in both modes and the other lever might be the safety, so, eh?

  29. Interesting concept to move the barrel instead of the bolt but the question is why do that what would any advantages be? If this was from 1918 or something when automatic weapons were new id understand why someone would try that but why would someone try that after moving bolt guns were already well established?

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