Pivoting Chamber - Caseless Ammunition

No, the LSAT type chamber will have the same kind of gas seal problems as revolvers.

>>33956406
Are you retarded? LSAT uses licenced G11 technology. LSAT uses the same two piece expanding chamber in its caseless variant as the G11 because it's proven and gas tight.

The pivoting chamber of the cased telescoping variant of LSAT is pure shit. It's basically just a one-chamber alternating revolver, which is a stupid idea for a high powered rifle as it exacerbates the problem of gas leakage out front that cased telescopic ammo suffers more from than conventional ammo. Plus, the completely pants onhead retarded idea of a pusher rod from behind to expel the case is a prime safety hazard, as it may set off rounds where the primer failed to ignite when the chamber is not in battery.

>>33956969
>two piece expanding chamber
I haven't heard of this, please you tell me more.

Also about that primer safety concern, aren't the bullets like completely seated inside the plastic case? Are they really poking out so much that primer ignition could be a problem?

File: g11_chamber.png (128KB, 350x366px) Image search: [Google]

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>>33958049
The G11 has a two-piece chamber, such that the pieces overlap in the middle. The chamber rotates from the loading position into battery position by 90 degrees. The bullet is loaded from the top downwards. Of course for this rotation to be possible there has to be some clearance. So the poblem is how to make that gastight.

This is why the chamber is in two pieces. The ignited propellant drives these two pieces apart, but only so much that they achieve obturation at the front and back and still overlap in the middle. It also presses the inner protrusion of the overlapping middle part against the outer protrusion of its partner from the other piece to seal the middle, too.

>>33959458
Interesting, would you happen to have more pictures/diagrams of this chamber design?

File: G11 Patronenlager als CAD-Zeichnung.jpg (125KB, 989x697px) Image search: [Google]

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>>33959562
I have this drawing. But its rather hard make anything out if you're not that familiar with the weapon. The top left shows one piece, the top right a cross section of the other.

File: g11 chamber maybe.png (11KB, 1153x549px) Image search: [Google]

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>>33959654
Was it kinda like this?

File: G11 chamber.jpg (78KB, 256x518px) Image search: [Google]

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>>33958049
As to primer safety, take a look at this video:
https://www.youtube.com/watch?v=WlM8IHij6Hs#t=1m23s

The new cartridge is to eject the spent cartridge just by pushing on its base. But if the previous round failed to ignite in battery and is being removed as a supposed dud it may potentially got off in an out of battery position. There is no guarantee that the fact that the bullet sits inside the case the mechanical pressure of it pushing won't set of the round in front of it.

In the G11 this was recognized and dealt with by always rotating the chamber in the same direction. So if there was a supposed dud the new cartridge would push out the old cartridge downwards and it would push on the top end of the old cartridge, leaving the primer untouched. See pic related. But this you cannot do with the design of the LSAT chamber.

File: 1494788355408.png (12KB, 1153x549px) Image search: [Google]

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>>33959787
Yes but they always overlap in the middle so that if the chamber is under pressure the overlapping parts are pressed against each other so that in the middle, too, no gases escape. Conceptually like in this adapted pic of yours. But I think you can see the sealing lips in the drawing.

File: b9221dfc0da3b698_800x800ar-660x438.jpg (33KB, 660x438px) Image search: [Google]

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>>33959851
I guess it is possible but i don't think that the tip of the bullet will actually even touch the primer of the round in front of it.

>>33960008
Normally it shouldn't. But you can never know, especially if there's some dirt in the chamber or a piece of plastic case that came off somehow and which may unfortunately act as mechanical extension for the tip.

File: G11 chamber 2.jpg (99KB, 710x720px) Image search: [Google]

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>>33959562
Found another pic. But with G11 pics you seldomly know which state of development it was in. The design changes throughout the program were pretty drastic. It was a long way till they got it right and some problems like obturation of the firing pin opening they only solved at the very end.

>>33960213
Why'd they even bother trying to keep it fully caseless btw? Why not just go with a thin plastic case to make it more weather proof and rugged.

>>33960265
The final rounds were already weatherproof and rugged.

>>33960265
Well, it started in the 60s. This was the time of SPIW and when the lessons of WWII were still fresh that infantry battles are a matter of who fires more rounds faster. So weight reduction via SCHV rounds was en vogue. But people also sought to increase hit probability, precisely because the only thing that was found to correlate with victory in infantry battles was the number of ronds fired, not caliber, not type of weapon, not the marksmanship skills of the soldiers or any other shooting range lore/myth.

And the idea was to increase rate of fire to such levels that multipe round are being fired before the recoil impulse hits the shooter's shoulder. But to achieve this the laborious extraction process of conventional cartridges had to be circumvented. That necessitated caseless, which also promised a drastic reduction in weight, which would allow more rounds to be carried, which increases your infantry's chances once more.

Probably also plastics technology wasn't there yet. Nowadays I'd consider plastic cased ammo superior because they, too, promise significant weight reduction but don't have to deal with all these obturation problems. But you have to put serious thought into the design still, because they, too, are different from conventional ammo and come with their own set of limitations and conditions.

Having said that the G11 solved all those problems. During the 1989 Bundeswehr field tests it achieved an average of 1 failure per 2000 rounds, which is very good for that time an still good today. I think the requirements for the M4 carbine are something like 600 MRBF. The actual reliability is higher, of course. The reliability of the best in the market like SCAR and HK416 is around 3000 MRBF.
But of course the engineering and manufacturing of the weapn and ammo made the G11 very expensive, too expensive for Germany after the end of the Cold War.

>>33960372
And yet they were carrier in those small clear plastic cases and not as loose rounds.

File: y_0d70c304.jpg (126KB, 807x605px) Image search: [Google]

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>>33959562

File: HKGray-G11action.jpg (219KB, 900x600px) Image search: [Google]

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>>33960539

File: bSIlZVY.jpg (371KB, 1280x1780px) Image search: [Google]

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>>33960582

File: _G11K2_07.jpg (127KB, 800x498px) Image search: [Google]

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>>33960600

File: G11_Schnittmodell.jpg (988KB, 3553x1595px) Image search: [Google]

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>>33960617

File: G11_k67982_German HK G11 4.7x33mm internal works- feed schema.jpg (88KB, 788x607px) Image search: [Google]

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>>33960638

File: g11 diagram.jpg (68KB, 500x366px) Image search: [Google]

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>>33960659

File: g11k2.jpg (134KB, 1044x383px) Image search: [Google]

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>>33960678

https://www.youtube.com/watch?v=n6JWCEmCgD8

File: G11_ammo_close_up.jpg (225KB, 1152x864px) Image search: [Google]

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>>33960690

File: 4_73caselessG.jpg (46KB, 944x460px) Image search: [Google]

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>>33960703

>>33956969
please dont use the R word

File: H&K_G11_Caseless_Ammunition.jpg (363KB, 950x405px) Image search: [Google]

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>>33960718

>>33960729
Yeah, I overreacted

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>>33960741

>>33960760
wtf i hate h&k now

File: _G11K2_01.jpg (65KB, 800x463px) Image search: [Google]

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>>33960760

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>>33960784

Aaaaand I'm done.

>>33959654
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>>33960523
Disposable magazines were a hot trend at the time, and STANAG mags were supposed to be disposable as well, the clear plastic cases would've been actually disposable and kinda handy

File: cork screw firing pin.png (543KB, 930x1327px) Image search: [Google]

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>>33961009
Well, as I mentioned in another post some problems they only solved very late in the program. One problem was obturating the firing pin hole of the chamber. This is a problem specific to caseless ammunition. In cased ammo the way the primer is integrated into the case achieves obturation. But with caseless this is a potential gas leak. A normal firing pin would allow gases to escape backwards. And you can't make the manufacturing tolerance too tight because this increases wear.

They tried to outfit the firing pin with some kind of collar so that the pressured chamber would press that against the rim of a hole, but this simply wasn't fast enough because the firing pin has to move there a relatively large gap at the point of ignition. And it takes time to reverse the momentum of the firing pin until its collar is pressed against the rim.

The solution was the cork screw firing pin. This design allowed the collar to always sit tightly near the rim. And the firing pin could hit the primer without the whole pin getting forward momentum as it only performs a rotational movement. Gas sealing is achieved nearly instantaneous.

File: various G11 chamber designs.jpg (341KB, 1637x1487px) Image search: [Google]

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>>33961009
They experimented with different chamber designs. In between also a three piece chamber.

>>33960690
Wtf I hate NATO now