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ALBPM
June 07, 2007, 06:09
I'm still fighting issues with my 223 FAL.

I went over to Vince's who had borrowed Ratas' headspace gauges to check headspace and he noticed that the slightest pressure on the gas tube would make the piston bind. So, a few days later I used a file and some sandpaper and opened up the guides in the upper receiver and gas tube nut to give the piston some more room.

I noticed some scoring on my gas piston when I had it out and was wondering if binding would cause this or what.

Here's a pic for the experts.

http://mywebpages.comcast.net/pmahl/piston.jpg

I don't see this on any of my other FALs.

SIG552
June 07, 2007, 06:37
Hows the condition of the Gas Tube Nut? Can the piston run back and forth freely and without binding? It looks to me like the piston is getting jammed into the GTN and then whacked forward by the BC.

SIG552

vmtz
June 07, 2007, 08:32
Did it change your feeding issues?

Vince

ALBPM
June 07, 2007, 09:33
Originally posted by vmtz
Did it change your feeding issues?

Vince

Haven't been shooting yet....

ALBPM
June 07, 2007, 09:35
Originally posted by SIG552
Hows the condition of the Gas Tube Nut? Can the piston run back and forth freely and without binding? It looks to me like the piston is getting jammed into the GTN and then whacked forward by the BC.

SIG552

Moves freely now. It did before filing some more out of the GTN except if there was the slightest press on the Gas tube.

W.E.G.
June 07, 2007, 10:30
That pic is very good to show the marks you are referring to.

However, the pic sucks for identifying which end is the front versus the back.

I suspect circumferential marks are more likely a function of the tooling used to manufacture the piston, rather than some impression left from an unwanted constriction during actual use of the piston.

bykerhd
June 07, 2007, 14:35
from W.E.G.
I suspect circumferential marks are more likely a function of the tooling used to manufacture the piston, rather than some impression left from an unwanted constriction during actual use of the piston.
That looks right. But, there is also some scratching across those marks. Dragging on something maybe ? Or, maybe the piston tail is oversize ? Maybe ? Or bent ?

chrsdwns
June 10, 2007, 17:30
FWIW, I had to replace the factory Imbel gas piston on a 223 SAR 4800 because it was binding as well.

A Stg 58 piston worked just fine.