How Does It Work: Lever Delayed Blowback 

I don't blame him, I just wanted to see it again

Hey. Psss, wanna see my FAMAS?

Vivre le Clarion!

you love anything phallic though, amirite Caulk

When I saw the title, I knew he would show it. I really like the FAMAS.

Went to see this. Not disappointed ^^

Well, the FAMAS is a FAMouS example.

No bueno, need MAS produced.

@@DivingHawker Oh ! Le jeu de mot laid...(le jeu de mollets !)

No, you call it amplification d'inertie.

That is a more accurate name

Zorg Enterprises!

@@smorrow In German it is "electrical tension".

Lmao also that M43 it's pretty rare

True.

TheGoldenCaulk Yes, yes I have

😂😂😂

Sh shamefur dispray!

That's like a single mag's worth of fouling my friend this is delayed blowback

oh yes, he fired a full load into it this morning...

If I ever figure it out and get it working I'll post a video on it, probably not any time soon

YES!

I used to work for a gun smith that built a 308 lever delayed blowback. So a PCC might be on the table for this.

It really does seem like a good idea for SMG's and PDW's. Yet it never caught on, which makes me wonder if anything is wrong with it.

I usually watch these videos before I go to sleep and my tired ass thought that was some sort of gas piston, ww1 style lol

Ce n'est pas un système de verrouillage car il n'y a pas d'interposition au mouvement de l'ensemble mobile fermé sur la chambre du canon, autre que l'inertie de la masse additionnelle...L'expression "delayed blow back"... en francais "ouverture retardée"... est vraie ! C'est l'objet d'un brevet français déposé en 1947 et paru en 1949...L'AAT 52 (mitailleuse ou fusil mitrailleur) utilisait ce principe...avec culasse ouverte ! Au plan de la physique des solides, l'inertie est une FORCE qui s'oppose au MOUVEMENT...Donc il faut écrire : F = M x gamma ! Imaginez l'appareil d'essai suivant : un canon vertical avec la chambre en haut...on met une cartouche en chambre...on pose sur le fond de l'étui une masse M representant un ensemble reculant ou une culasse seule...et par un moyen simple (effacement d'une goupille) on percute l'amorce...l'expansion gazeuse éjectée la balle vers le bas (une plaque ductile amortira l'effet) et l'étui vers le haut...par un moyen simple, un cliquet élastique, on arrêtera la masse M à l'instant où elle atteint son apogée h c'est à dire une vitesse verticale nulle...On obtient ainsi le critère de qualité propulsive de la cartouche : v initiale culasse = racine carrée de 2 gamma x h ! A partir de masses differentes, on peut établir la valeur fondamentale de tout le système reculant c'est à dire la vitesse d'ouverture de la culasse de masse M...Cette expérience m'a permis de tester les lots commerciaux de la gamme .222, .222 Magnum et .233 en plus des gammes militaires et de comparer leurs performances intrinsèques vers l'arrière...vers l'avant c'est connu la vitesse initiale des balles est mesurée par des boucles de détection...On peut faire cela pour tous les calibres...Et on en deduit par le calcul tout un ensemble de critères dimensionnants !

Has Ian done "blow - forward" actions yet?

@@kbjerke Indeed he has, here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rk8G5-cJvR8.html

nice shot!

FAMAS, o yEA!

I'm still confused.

I'm still confused how does pressure get transferred to the bolt carrier if its locked it seems as if the pressure has no way to force the bolt open

@@CenlaSelfDefenseConcepts It's not locked. It's just that for the bolt to move back a tiny bit the bolt carrier has to move back a lot. If you listen to what Iain says carefully he says "the accelerator lever is locked into the receiver", the bolt *is not* locked.

The vz58 is a short stroke gas piston gun. Although its locking wedge does look similar to the FAMAS lever.

@@ForgottenWeaponsthat is what I was trying to infer, the Czech's have a very interesting way of designing guns

A pistol system would put more weight at the front (balance was an important design element in the FAMAS, and it shows) and would make it more difficult to free-float the barrel.

@@ForgottenWeapons thanks for the quick reply! I was not expecting to hear from The Man Himself after asking this question! You've really made my day, honestly.

All the gas system (gas port, gas piston, gas cylinder, op-rod, a spring in case of short stroke) is replaced by a single adjunctive part, the lever.

Sure, the majority of 9mm submachine guns are simple blowback mechanisms firing supersonic projectiles.

Pcm979 I think Ian clipped some footage from that video to use as an example and just put a new voiceover over it. I’m pretty sure those are the exact same shots as in the first video.

Yes, it's a clip from that video.

Exactly. The case is still extracted in high pressure but not so much that can destroy rifle or harm shooter.

Lever delay is one of a few ways to keep the bolt from opening too soon after firing. If it opens too soon the high pressure could cause the cartridge case to rupture resulting in injury and/or damage.

Danuvia 43M

I may be misunderstanding but if the lever were acting to push the bolt carrier forward it would act like a simple blowback (Maybe less so since the leverage is now effectively pushing the bolt backwards) until the lever has moved its full travel, then the bolt would rather violently impact the carrier rather than gently following along with it

Delayed blowback mechanism in itself reduces somewhat the feeling of recoil.

@RocketSurgeon AFAIK, the blow forward systems have a terrible felt recoil, though I´m not quite sure why. I was thinking of some mechanism where the mass is forced forward, similar to the AK101, but where the the bolt has a disadvantage to overcome. Thinking about it, I guess it would add to the impulse rather than reduce it, but it still boggles my mind...

@@edi9892 Blow forward systems have a huge perceived recoil due to the kinetics changing direction entirely at points in the cycle If you brace for the recoil coming backwards but there is a forwards lurch then backward movement it has altered your stance and lost the bracing Delayed blowback however simply softens the felt recoil as you are already braced and it is now a lesser impact over a longer period

Just that pesky extraction issue...

Joel Rigby Fair. Fluting the chamber isn’t orthodox easy but isn’t that difficult to do either. A little electrical discharge machining perhaps.

The roller-delayed system runs on the same principle and it widely adopted. I think that what happens is that both the long stroke and short stroke piston design are easier to copy-paste.

What komn87 said. So much r&d has gone into long stroke and short stroke piston design, as well as whatever the system is the AR-15 was again (not direct impingement), that they've taken over as the go to methods, along with some roller delays in the mix (which IIRC were generally thought of as harsher to shoot by comparison to AR-15 and short stroke guns, but I might be wrong). And IIRC in the FAMAS video Ian did mention that while the lever delayed blowback system is very reliable and simple when using the ammo it was designed for, it can be a bit picky about the bullet weights, powder loads and casings, and might require modifications to move from one type of round to another, like how they had to modify the FAMAS to run reliably and accurately with NATO spec brass cased ammunition, vs. the original French steel cased 5.56. You can't simply adjust the gas pressure etc. on the FAMAS to cope with different loads, you can only do things like change the fluting of the chamber, the length of the levers and the mass of the bolt carrier to change the dynamics of the gun.

In theory the system is as safe as pure blowback. It simply exchange the mass of the bolt with the acceleration of a part of it. In practice, using riflle ammunitions, it's difficult to fine-tune, being always on the verge of having a too harsh extracion (not enough mechanical disadvantage) or not having enough power to cycle the action (too much mechanical disadvantage).

It applies a bit more mechanical counterweight for the gas to push.

@@EuroRhodes My bad, I confused the charging handle's rod with a gas piston when in fact it's right there in the system's name, it's a "blowback" .

It trades mass for speed. To accelerate a mass to double the speed in the same time, you need four times the energy, so introducing a lever that accelerates the carrier in respect to the bolt face, you need less weight than in a pure blowback system. .

Same principle

You can do the maths yourself. A Sterling machine carbine, which I was familiar with, has a 7.7 inch barrel [we'll ignore headspacing] which is 0.64 feet. NATO 9mm goes at about 1800 feet per second. That's 0.00035 seconds to clear the barrel. Slowing the breach opening isn't actually the trick, it's making sure there's enough power left in the system to reliably cycle the gun

Since there are St Etienne G3s, I could. :)

small cuts in the chamber which allow gas to flow around the cartridge case to overcome static friction easing extraction. lots of info on the g3 and its fluted chamber if you want to know more.

The same delay mechanism is used in the French AA52 7.62x51 machine gun which is still in (limited) service after over 50 years, so it's probably fairly robust :). (There was even an experimental version in .50BMG).

Kiraly 43M