[ Gas-Delayed Blowback Pistols ]
Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and today we are going to take a look
at the gas-delayed blowback operating system.
I have an assortment of gas-delayed
blowback pistols here to show you because
... several of these work a bit differently
than several others, and I have almost all of
the common production gas-delayed blowback pistols here to take a look at.
The notable exception of course is the Walther CCP,
which I have no particular reason for not having, just I never ended up getting one.
However its operating system is pretty similar to kind of what we'll call
the "standard gas-delayed blowback pistol", if we can say there is such a thing.
Let's begin with probably the most recognisable of these pistols, which is the HK P7.
This of course was developed as a ... West German police pistol.
And in addition to being gas delayed, it has this rather interesting
and fairly unique squeeze cocking mechanism where this is what actually cocks the pistol.
You can see the striker indicator back there.
And the idea of this was that if you don't actually
have a firm grip on the pistol it is totally safe,
because the striker has no tension on it and it can't possibly fire.
So most people are probably more familiar with the squeeze cocking mechanism
than they are with the gas-delay system.
So let's take it apart, it's a pretty easy one to take apart.
Push the disassembly button, we are going to lift the slide up, slide it forward.
And we will see what you will start to recognise
as the most common ... style of gas-delay mechanism.
So we have this gas piston here, the rings on it are essentially gas sealing rings.
Each one of these presents a difficult barrier for gas to get past.
Not totally impenetrable, that's why you have a series of them,
but each one of these segments has less and less gas pressure in it as you go down.
So it's essentially a way to basically seal the system.
Now one might ask why would you design a gas-delay blowback pistol,
it has some downsides, what ... is the benefit from it?
Well, one of the prime benefits is that you have a fixed barrel.
So the barrel is attached to the [frame], it never moves,
that makes it easier to make a pistol very accurate.
There can be very accurate pistols with tilting or otherwise moving barrels,
but all things being equal, it's easier to get that
level of accuracy if the barrel doesn't move anywhere.
So the way this style of system works is that there is a gas port right there.
That hole is actually drilled clear through this mounting block,
the gas port in the barrel is only on the underside.
So this is just a remnant of a machining operation.
When the pistol fires, as soon as a bullet goes in front of that port,
which is essentially immediately upon firing,
gas vents down into a little chamber, a cylinder down here under the barrel.
And that is where that piston is sitting.
So if we just drop this on top.
The piston right here is in front of this gas cylinder.
And because the barrel is plugged by the bullet as it travels down the barrel,
gas pressure builds up in that piston,
forces this forward and prevents the whole slide from moving backwards.
Now in reality it's going to start moving very slowly.
All delayed-blowback systems, because they are not fully technically locked
the slide does start moving immediately, but it moves extremely slowly
because it's working against a great deal of pressure here.
And then of course once the bullet has left, all of that pressure can vent
up through the gas port and "whoop" out through the barrel.
Then the energy that the slide has already developed moving back
has a lot less resistance and the pistol cycles.
So this is the typical style that you'll see for gas-delayed pistols.
If the HK P7 is a particularly expensive gas-delayed pistol,
the Heritage Stealth is a particularly inexpensive one.
I think this cost me less than 150 bucks back when I bought it.
This is a design that originated in South Africa in the early 1990s,
developed by a guy named Alex DuPlessis.
But ... he's South African, so there's like a thousand people named Alex DuPlessis.
At any rate, he wanted to come up with a compact lightweight backup pistol
for soldiers, for potentially airmen, for law enforcement and he developed this.
Now this was ... originally manufactured by Truvelo in South Africa,
they later sold the tooling to Heritage Manufacturing in the US.
... The design was actually produced by Wilson Combat for a brief time.
But this pistol overall, between the US and South Africa,
was manufactured in a bunch of different calibres from .380 up to .45 ACP.
This particular one is 9mm with a 10 round double-stack magazine, a polymer frame.
It is a very light pistol, and that is one of the other benefits of a gas-delayed system.
You can have a simpler action than a locked breech system.
But because you have some mechanism reducing the amount of force acting on the slide,
you can have lighter weight components compared to a simple blowback.
So simple blowback depends entirely on the mass of the slide to open slowly enough
to not have the cartridge open up and explode because pressure is too high.
This, well maybe we'll just pop this open, this disassembles basically the same way as the P7.
We've got these two little squeeze tabs here, I'm going to push those together.
And then ... there we go, lift the slide off.
You'll see the slide once again lifts off the top of the gun.
We have the gas piston there, we have a fixed barrel with a recoil spring located around it.
And we once again have our
(I keep calling it a gas chamber which is a really bad term to be using)
but that's the cylinder and that's the gas piston.
So this works essentially identically to the [P7], same thing.
... You can see in fact there's the vent hole.
So this is drilled all the way through, but there's only a vent hole in the bottom of the barrel.
That's just for ease of manufacturing.
And gas, when you fire, pressurises this piston which holds the slide forward.
And it can do this in cartridges like .45 ACP and .40 Smith & Wesson, as well as 9mm.
And the result is you get a fairly lightweight, fairly simple,
fairly compact pistol with a relatively high capacity.
Now this one's cheap because the manufacturing quality was ... maybe not great.
And it was never a particularly successful pistol,
but it's a cool example of gas-delayed blowback.
I have one more example of this style of system,
this time on a Norinco Model 77B, which is a really odd pistol.
You know it's funny, the gas-delayed pistols don't ever seem to be content
to just have a weird operating system, they've got to have some other odd feature.
On the Norinco it is that the front of the trigger guard
lets you cycle the slide with your trigger finger when it's working and not ...
yeah so this one the parts are starting to get worn, it doesn't always work.
But that was the idea and really strangely, this ... appears to have been copied
from a patent by none other than Ole Krag from like 1910
which also had this ... trigger-guard slide-activation feature.
Anyway for this guy we are going to disassemble it by rotating
the selector all the way to the vertical position.
And then we do the same thing as the other pistols, pull the slide back, lift up, pull it off the front.
Once again you see we have a fixed barrel, recoil spring on top of the barrel.
There's our gas piston. The Chinese only put three sealing rings on it, for better or worse.
Now you can see a spring in the bottom here, but that's just the spring for this trigger guard lever.
The tube underneath it right there, that is your gas cylinder.
So once again this works the same way. You can even see that same manufacturing step right there.
It's not really clear to me what the design intent behind the 77B was.
Some of the stuff coming out of China, like we just don't have good access
to information on the original market plan and who this was supposed to go to.
So this one's kind of a mystery to me.
Alright, so there's the standard form of gas delayed pistols.
And by the way, the Walther CCP is this same basic system as well.
And always recognisable by this gas piston hanging off the front of the slide.
Alright, now let's move on to something that's a little bit different
from that basic standard system, the Laugo Alien.
Once again, the Alien is not content to just have an odd operating system
it has to also have all sorts of other really cool features.
The most distinctive one on this is ...
well, the sights are not on the reciprocating part of the slide.
So whether you have optic or irons, they stay in place
while the slide operates, which is really cool.
Anyway to disassemble this guy I'm just going to pull that pin,
and then push the top rail assembly forward.
There we go, trying to be gentle with that.
So that's the hammer for firing.
On this guy, instead of having that piston on the underside of the slide
operating below the barrel, the Alien puts it on the top.
So we can actually take the slide out here.
There we go. Unlike the previous examples, the slide does not have the piston directly attached to it.
Instead on the Alien the piston sits above the bore (just drop it in place) above the bore right there.
So when the slide cycles it's pushing back here, and compressing the recoil spring.
The ... physics of how this operates are the same as these other systems.
We have a gas cylinder right here, gas piston right there.
As soon as you fire, pressure from the cartridge here pushing back
is going to try to move the slide backward.
Which means the piston has to push into that gas cylinder,
which is very difficult because all the pressure in the barrel is acting on that gas piston.
So fundamentally the same mechanism, but the execution here is substantially different.
And there are two benefits from this style of execution.
One of them is the bore, because the bore is located below the gas system
you can actually locate the bore much lower in the pistol, which gives it a very low bore axis.
Which makes it really easy to shoot fast without it climbing off target.
That's not something that was the primary concern for example of the P7.
The P7 was designed first and foremost around everyday carry safety.
The Heritage Stealth (originally called the ADP) was designed around light weight and compactness.
While the Alien was designed around being an extremely good competition gun.
So we can see the different intended roles of the pistols
influencing the specific design elements that go into them.
Now last but not least we are going to get to the Austrians with the Steyr GB here.
This is a pistol that was developed for Austrian
military trials and ended up losing out to the Glock.
It is gas delayed, but it is a substantially different gas-delay system.
So drop that down, and I can then rotate this muzzle cap ... to there, pull it out.
This is an essential element of the operating system.
Once that's out I can pull the slide back
and lift it off, there we go, pull the slide forward.
Now first thing you notice here, well maybe not the first, but in the context of this video,
the first thing you notice is there is no gas piston there. It kind of looks like a regular slide.
That's because the ... gas piston is the barrel itself,
and the gas cylinder is this plug that goes in the front of the slide.
So when the gun is assembled and in a firing position it looks like this.
And there's a hollow chamber inside this plug here.
You can see we have two big gas ports in the front of the barrel, there are our gas rings.
So ... essentially the same really high level concept
of as long as the bullet is in the barrel it's going to pressurise this area.
Which is going to push forward on the slide, which is going to slow the slide down
and prevent it from opening before chamber pressure has dropped.
Now it's interesting on the GB, this doesn't pressurise
until the ... bullet is halfway down the barrel.
On all of these other guns the gas port is located essentially immediately in front of the chamber.
So the moment the bullet starts moving, gas pressure builds up
in the delaying mechanism, not so much on the GB.
So part of the solution for that is there is more mass in the slide here
to prevent it from getting moving quickly.
But this is the only real production version of a pistol like this, with this style of action.
Some people are going to look at this and say, "Ah, that's like the
last-ditch German Gustloff carbine, the VG1-5.
... I have covered the VG1-5 in another video, we'll talk about it separately.
... It looks similar, but the VG1-5 does this ... essentially
as a buffer mechanism, not as a delaying mechanism.
So the Steyr GB is kind of one of a kind sort of design out there.
Well there you go, there's a nice assortment of gas-delayed blowback pistols
a perfect microcosm of Forgotten Weapons in general
because it's such a weird obscure bunch of pistols that we have here. ...
I probably should get a Walther CCP just to complete the set here.
At any rate, hopefully you guys enjoyed taking a closer look at these.
If you did let me know, and perhaps we'll follow up
with some other overviews of odd mechanical operating systems.
Thanks for watching.