Why are there 2 types of short stroke gas piston systems?

[kal]

There's the multi piece design like the ar180b
http://2.bp.blogspot.com/_ICuLB148bJU/SMxEC-okAgI/AAAAAAAABjg/cCy5pEzwGLQ/s1600-h/IMG_8872a.jpg

And then there is the one piece design...

fal
http://marshhawkarms.com/images/FAL_PISTON.jpg

vz58
https://www.apexgunparts.com/images/VZ58/US%20Made%20VZ58%20Gas%20Piston.jpg

What does one offer over the other?

[Aries144]

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[variablebinary]

I speculate that it has something to do with how the piston assembly is maintained.

Long since piece oprods like POF and LMT slide right out.

Segmented piston systems like LWRC, ACR, and the HK416 dont slide out, and have to be accessed with some additional work

[Thomas M-4]

Multi-sectional are for ease of take-down and or manufacture.
Short stroke: The piston moves less than the length of the cartridge.
Long stroke: The piston moves the entire length of the cartridge.
Multi sectional op-rods will not have an effect as long as they act as one during the operation.

[MPi-KMS-72]

FWIW-There is also the M1 carbine type short stroke piston (more like a tappet). It is kind of neat but I am not sure it has ever been applied to another rifle?

[kal]

FWIW-There is also the M1 carbine type short stroke piston (more like a tappet). It is kind of neat but I am not sure it has ever been applied to another rifle?

I think the fs2000 and scar uses the same setup.


Multi-sectional are for ease of take-down and or manufacture.

I don't know about the take-down part. I mean how hard is it to remove a solid op rod. Watch this disassembley of a vz58 rifle. notice at 1:23 and 2:23.....


http://www.youtube.com/watch?v=1sxjdJLkhRg

[Thomas M-4]

If a multi section piston/ rod cycles as one when the weapon fires the only reason I can see is for easy manufacture and or assembly.

Does any body have a linky for a good illustration or explanation on how the AN-94 operates ?

The vid showed a one piece gas piston/ rod I think we are not on the same page.

[kal]

The vid showed a one piece gas piston/ rod I think we are not on the same page.


Yes it was one piece, whereas something like the AR180B has a three piece design which includes the op rod, the connector piece, and the "cup" or whatever the hell it's called.

That's what I'm trying to figure out, why are there multi-piece vs single piece short stroke op rod/piston assemblies?

It doesn't seem difficult to take down either design so there has to be other reasons.

[MPi-KMS-72]

Yes it was one piece, whereas something like the AR180B has a three piece design which includes the op rod, the connector piece, and the "cup" or whatever the hell it's called.

That's what I'm trying to figure out, why are there multi-piece vs single piece short stroke op rod/piston assemblies?

It doesn't seem difficult to take down either design so there has to be other reasons.

IIRC the AR-180 has system was taken from the SVT-40:
http://www.surplusrifle.com/svt40/rifle/index.asp

I have wondered why they were multi section- I assumed that part of the reason was to make disassembly easier however to be honest I have not given it much more thought until tonight. ;)

[Aries144]

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