SKS gas cylinder becoming loose when hot

Sardaukar

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Yesterday I was doing some serious shooting with my SKS for the first time and I noticed that the hotter the rifle got the looser the gas cylinder/handguard got. When the barrel was almost burning hot I could wiggle the gas cylinder 3-4mm. Is this normal?
 
Never noticed that on any of my many SKS rifles over the years. Perhaps your gas tube lever moved a bit and that made it looser? Metal is supposed to expand when it gets hot, making it tighter. That is quite odd.
 
Yesterday I was doing some serious shooting with my SKS for the first time and I noticed that the hotter the rifle got the looser the gas cylinder/handguard got. When the barrel was almost burning hot I could wiggle the gas cylinder 3-4mm. Is this normal?
Mine does that as well. 3-4mm should be ok
 
If it loosened when hot, something is loose somewhere else. I'd consider shimming the back end of the gas tube. A piece of shim stock, cat food can or Coke can aluminum with a suitable hole for the piston would do the trick.
 
Yes, it tightened up when it cooled, so I'm not too worried, just curious.

And it wasn't actually burning hot, more like very hot, but a normal very hot.

I might shim it if it annoys me enough.
 
Mine is actually loose all the time so I wouldn't worry too much about it. If you consider how it's secured, its a wonder any of them are tight at all...

As long as your gun cycles, then you have nothing to worry about.
 
Not an sks expert but am familiar with them, I would estimate the thermal growth of the bbl at .020 to .030" at 220 F dependant on the actual metal used in manufacture and the temperature differential from a cold to hot bbl. The metal grows out with heat and contracts with cold. The gas tubes aren't a tight fit to begin with so I would expect to see some movement from the gas tube with a hot bbl.
 
Ever since I changed the stock on my sks the handguard/gas tube has had a bit of play (not quite as much as yours, but close). I've put at least a crate or two of ammo through it since and haven't had a problem yet... As well, a friend of mine has a norenco sks and his has a couple mm of play even when cold and he doesn't seem to have any problems with it. If I were you, I wouldn't worry about it...
 
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