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Old 01-30-2012, 09:16   #1
BFB
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? Norinco Gas Piston Sticking

Hi all,

I am normally in the Mini 14 section here, but I recently picked up a Norinco SKS, and I think I have a problem with the gas system.

I haven't tried to fire it yet, but decided to tear it down and inspect everything before firing. It is now totally clean of all cosmoline, and everything looks good to go except for the gas tube/piston.

Here is what I found: It seems to me that the gas piston should work back to where the top of the piston would be back beyond the two opposite vent holes in the gas tube. Is that a correct assumption? ... Just sliding it by hand, the piston in this rifle doesn't go back nearly that far. It will move just over an inch backwards, and then stops dead. I cleaned and polished the inside of the gas tube to where it actually shines, and then checked the piston for burs. It all looks good to me, but still won't move any furthur back than what I described.

Maybe I should take it to a machine shop and have them burnish the inside of the tube? ... Maybe buy a new tube? ... Info or suggestions?

Thanks,

BFB
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Old 01-30-2012, 14:00   #2
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Sounds normal, it only needs to move an inch or two. The piston on my Romanian travels about 1.5" into the tube before it stops.

Remember, all it is doing is hitting the op-rod that then in turn will move the bolt carrier. It's not like the piston has to reach all the way back to the receiver.
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Old 01-30-2012, 15:41   #3
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GDKPIKPWG,

Thanks for responding.

I thought perhaps this might be normal, because of how clean I got it.

Here is what is curious to me: If the gas piston rod drives the spring returned operating rod rearward, which it most certainly does, then this rear operating rod can only move that same distance. ... Obviously the bolt and the bolt carrier go back much further than that during cycling.

Is it such that the bolt/carrier operates on not only a gas driven piston, but also some recoil action as well?
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Old 01-31-2012, 05:53   #4
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It does seem weird when you think about it moving at a normal speed, but at the speed it moves when a shot is fired there is more than enough power imparted to send the bolt flying back.

Take it out and shoot it. At worst, there is a problem and your SKS will function like a straight bolt action until you fix it (like a yugo with the gas valve shut)... But more than likely, it will work fine.
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Old 01-31-2012, 17:57   #5
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Yep, she's clean as a whistle, and right now I'm waiting on a recoil buffer, tech sight, and the spring kit for the firing pin. As soon as I get those things, I'll put 'er together, and take 'er out for a range session.

Thanks GDK.
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Old 01-31-2012, 20:41   #6
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Keep us posted. I am a lover of the SKS. Just really wasn't sure how to respond to your question. They are a wonderful rifle.
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Old 01-31-2012, 21:46   #7
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Will do Mosinka.

Funny thing is, a good friend talked me into this rifle, and I didn't think too much of it at first, but while tearing it down, and looking it over, I got to thinking, "Hey, this is kinda' neat."

Anyway, after I get er' up and running, and the weather co-operates for a range trip, I'll post back.

BFB
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Old 02-01-2012, 18:23   #8
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Hey all,

I got a bit of good info today from a guy who is "in the know" on SKS.

From what he told me, it turns out that the piston and operating rod are only driven rearward about 3/4". This is because the operating rod spring binds up (read; comes to full compression) at that distance. From there the bolt/ carrier are driven all the way back from the initial thrust.

Thanks, and a tip of the hat to GDKPIKPWG. He nailed it.

BFB
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