Lever Delayed Musings

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Lever Delayed Blowback Musings. If you want more info on the FAMAS system and why they feel it's 'better' than the Kiraly system check out the patent on google patents: US Patent number: 3938422 The Russians also had their own flirtations with delayed blowback via a class 3 lever. The http://world.guns.ru/assault/as74-e.htm the Korobov TKB-517 was based on the Kiraly idea. Baryshev's system, which was probably inspired by kiraly: See here: http://world.guns.ru/assault/as87-e.htm Baryshev AB-762 and AVB-762 have some kind of weird tilting bolt head also. If I recall correctly Benelli implemented a Lever delay blowback system on one of their handguns. check this out: http://www.czechweapons.com/en/ They're a small company that is focusing their efforts on, to my knowledge,the most recent revision of this lever delay concept. Good patent info here, full description and good diagrams: http://www.czechweapons.com/en/data/283180.pdf It has at least 3 variants on lever delayed blowback, unfortunately at least one of them uses the lever itself as the hammer so it's only suitable (as is) for full auto open bolt guns. The other two (IIRC) can be used for closed bolt semi auto. another Patent seen here: http://www.czechweapons.com/en/data/pv-341-2006.pdf They also contain some disassembly videos in which you can see the bolt system and locking piece. Now as much as I like the idea of delayed blowback (No gas system, fixed barrel which can be free floated, Open breech face that's easy to clean and clear jams or check chamber... My biggest complaint is the roller locked system seems to involve some rather complicated geometry, and while the lever delay system seems a tad simpler in concept, it has one major disadvantage: The bolt 'locks' up behind the magazine, thus restricting the type of weapon you can stick it in. So I came up with a concept solid model assembly to test the idea of a lever delayed blowback system using a barrel extension (ala ar-15) instead of the receiver. The Main problem being the magazine normally being right next to the chamber, you really can't put a large locking shoulder there, and have the levers in the way of the magazine. SO I flipped the whole concept on it's head and decided to try having it lock ABOVE the chamber, not below it.

description

A brief summary of implementation of lever delayed blowback firearm methods. Followed by A theoretical application for a barrel extension based method.

Transcript of Lever Delayed Musings

Page 1: Lever Delayed Musings

Lever Delayed Blowback Musings.

If you want more info on the FAMAS system and why they feel it's 'better' than the Kiraly system check out the patent on google patents:

US Patent number: 3938422

The Russians also had their own flirtations with delayed blowback via a class 3 lever.

The http://world.guns.ru/assault/as74-e.htm the Korobov TKB-517 was based on the Kiraly idea.

Baryshev's system, which was probably inspired by kiraly:See here:http://world.guns.ru/assault/as87-e.htmBaryshev AB-762 and AVB-762 have some kind of weird tilting bolt head also.

If I recall correctly Benelli implemented a Lever delay blowback system on one of their handguns.

check this out: http://www.czechweapons.com/en/

They're a small company that is focusing their efforts on, to my knowledge,the most recent revision of this lever delay concept.

Good patent info here, full description and good diagrams: http://www.czechweapons.com/en/data/283180.pdf

It has at least 3 variants on lever delayed blowback, unfortunately at least one of them uses the lever itself as the hammer so it's only suitable (as is) for full auto open bolt guns. The other two (IIRC) can be used for closed bolt semi auto.

another Patent seen here: http://www.czechweapons.com/en/data/pv-341-2006.pdf

They also contain some disassembly videos in which you can see the bolt system and locking piece.

Now as much as I like the idea of delayed blowback (No gas system, fixed barrel which can be free floated, Open breech face that's easy to clean and clear jams or check chamber... My biggest complaint is the roller locked system seems to involve some rather complicated geometry, and while the lever delay system seems a tad simpler in concept, it has one major disadvantage: The bolt 'locks' up behind the magazine, thus restricting the type of weapon you can stick it in.

So I came up with a concept solid model assembly to test the idea of a lever delayed blowback system using a barrel extension (ala ar-15) instead of the receiver.

The Main problem being the magazine normally being right next to the chamber, you really can't put a large locking shoulder there, and have the levers in the way of the magazine. SO I flipped the whole concept on it's head and decided to try having it lock ABOVE the chamber, not below it.

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Here is my 'proof of concept' for a upsidedown barrel extension lever delay blowback with a 4:1 lever ratio. I can't guarantee it'll work, but at least the bolt carrier was forced back by the lever when contact solutions was turned on in inventor.

Part of me wonders if you did something like a telescopic UZI bolt you could actually have the lever fulcrum/shoulder be the SIDES of the barrel extension/barrel proper? This would certainly solve the issue of getting in the way of the magazine.

Anyway the pics:

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Overall view

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Minus Barrel Extension

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Bolt Only

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Carrier only.

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Close up of lever.

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Side view of system 'locked' (for some reason it's UPSIDEDOWN!

Lever fully deployed

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snails eye view of whole assembly (the 'sheet' on top would be your receiver or whatever method (guide rod?) you used to keep the delay lever in the rearward position for it's cycling trip.

Also note the carrier is not a hollow 'U' but becomes solid and holds the carrier, but has to have a cutout for the magazine clearance of course.

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To quote from the FAMAS manual:

- The amplifying lever, under the breech bolt thrust and by the actionof the two lower arms on the receiver bearing surface, pushes back theadded mass with a speed increased by the amplifying ratio.- The angular stroke of the lever is 45* and during this rotation thefollowing operations are effected :- Firing pin withdrawal.~ Extraction by means of the extractor fitted to the right or theleft according to the firer’s preference.- After complete rotation of the lever, the backward movement ofthe bolt is effected for each of these parts at the same speed and thecompression of the main spring takes place throughout the backwardmovement.- A new cartridge is presented when the breech has moved backbeyond the magazine casing.- At the end of the backward stroke, the bolt’s surplus energy isabsorbed by the shock absorber, which it compresses over a maxi-mum stroke of 25 mm.

Two neat things about this setup. The Firing pin of the FAMAS is retracted by the unlocking of the Lever itself, if you think about this it not only prevents the firing pin from EVER striking the primer until the weapon is locked up but also removes the need of a spring to help keep the firing pin from being stuck open and causing a slam fire. Also keeps the firing pin from developing forward inertia from a drop or the bolt slamming home. Very clever (IMHO).

Also the full auto gun, in addition to the main spring around the cocking rod (above the barrel) also has a lever enhanced recoil buffer to stop the bolt from battering the shooter/gun. Basically it has a coil spring that's above the bolt carrier parallel to the bore axis, and a metal lever rests against one end, and another arm is in the final path of the bolt travel. So in order for the bolt to move this recoil lever a little bit, it has to compress the buffer spring even more. This is similar to how some of those pocket pistols use lever arms as the main spring in theory.

One other aspect to consider as a benefit to this system: The bolt head is free of locking lugs, rotation, tilting, or other obstructions. You could clearly make the bolt head modular (like the savage bolt action or the saiga shotguns) without compromising the strength of the action, and as an added bonus you could implement a kind of ambidextrous switching ejection system on the bolt head, or a mac-10 style fixed ejector rod.

Anyway, a lot of possibilities open up in this system that are not easily achieved with rotating bolts, or bolts with rollers taking up most of their space.