SKS Gas Piston Question (update)

[DirtyRussianAmmo]

I recently bought a Sino-Soviet SKS and noticed that the gas piston does not move freely in the gas tube, I have to manipulate it by hand to make it move back and forth. The feel is gritty and it does not fall freely out of the tube when disassembled. The gas tube is clean and free of dents and dings. The piston rod looks straight, although the head of the piston does feel a little rough, but there are no obvious burrs. Note: The piston extension rod works freely and functions as it should)

Is this okay, normal? If not, could this cause FTF"s?

Thank you for your help.

[peppermintman]

I recently bought a Sino-Soviet SKS and noticed that the gas piston does not move freely in the gas tube, I have to manipulate it by hand to make it move back and forth. The feel is gritty and it does not fall freely out of the tube when disassembled. The gas tube is clean and free of dents and dings. The piston rod looks straight, although the head of the piston does feel a little rough, but there are no obvious burrs. Note: The piston extension rod works freely and functions as it should)

Is this okay, normal? If not, could this cause FTF"s?

Thank you for your help.

I would lighty deburr the edges of the piston, lightly. Solvent on a .22 patch in the narrow part of the tube should clean it up nicely. Had the same issue with mine. Fine now. Piston head showing friction marks?

[Vlad 11]

I would lighty deburr the edges of the piston, lightly.

I had a one doing similar . The piston was a little buggerd. Chucked it in a drill and gave it a a quick spin in some 320. Did the trick, no more hanging up

[NOTABIKER]

i rub the piston with scotch bright, clean the tube. it should slide back and forth freely.. i lightly oil the tube also. i clean the tube every time i shoot my SKS. i would not oil the tube at all if you are not going to clean it every time. no oil is better than oiling it if you are not going to clean it. the oil will attract powder residue.

[BroncoBob]

Had a couple of those and I just cleaned it up real good with some oil and wet dry sand paper rubbing very lightly. They all worked smooth after that.

[DirtyRussianAmmo]

Thanks to all, lots of good suggestions here. I'm going to lightly polish the piston, see if that frees it up.

[SVT-40]

Are you sure you removed all the cosmoline from the gas tube? Sometimes it's really gummed up...

[bohoki]

most often the tube gets a little ring of residue buildup and it feels like the piston is stick but its only sticky in the front section but further back in the actual actuation area its smooth sailing

[DirtyRussianAmmo]

Are you sure you removed all the cosmoline from the gas tube? Sometimes it's really gummed up...

Yes, tube is free of cosmoline.

[DirtyRussianAmmo]

most often the tube gets a little ring of residue buildup and it feels like the piston is stick but its only sticky in the front section but further back in the actual actuation area its smooth sailing

The piston gets free, moves, then seems sticky again. Not just in front of tube.

[DirtyRussianAmmo]

How far should the piston move freely in the gas tube? Inch and a half? Two inches?

[NOTABIKER]

THE PRESSURE FROM FIRING THE GUN AND THE SPRING PRESSURE RETURNING THE PISTON WILL OVERCOME SOME STICKING.

[DirtyRussianAmmo]

THE PRESSURE FROM FIRING THE GUN AND THE SPRING PRESSURE RETURNING THE PISTON WILL OVERCOME SOME STICKING.

Yes, that makes good sense, thanks.

[Gutz]

I think your SKS is fine. If it moves too freely, no bueno. Just a dap of oil when you reassemble it and leave it be unless is gives you cycling issues.

[DirtyRussianAmmo]

I think your SKS is fine. If it moves too freely, no bueno. Just a dap of oil when you reassemble it and leave it be unless is gives you cycling issues.

Had cycling problems at range yesterday. This is the second time I've shot the gun. First time ran flawlessly. Yesterday, went through about twenty rounds, then FTF's occurred (all the same ammo was used, Tula 122 gr FMJ). It started acting like a bolt gun, firing after I manually cycled the bolt. I did notice the bolt was very hard to pull back, but when I cycled it, the round in the chamber was properly extracted. The primers on the FTF's were dimpled. I have not checked the headspace, but did notice that the bolt lug locks properly in place when closed. Bolt and carrier are matching numbers. Bolt has been stripped and cleaned. Firing pin rattles freely.

Anyway, got home, took rifle apart, noticed how sticky the piston was, thought I'd start with that. The rifle chambers and extracts rounds smoothly by hand. Any trouble-shooting suggestions would be greatly appreciated. Thanks!

Note, put the rounds with dimpled primers in my Saiga and shot them no problem. So they weren't bad rounds.