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SKS piston

Discussion in 'Gunsmithing and Repairs' started by ChaoSS, Oct 13, 2013.

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  1. ChaoSS

    ChaoSS Member

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    I'm trying to de-Cosmoline an SKS I picked up, and I can't get the gas piston out. Am I going to damage it if I just go at it with a nail set and a big hammer? Do I need to get some actual brass punches?


    Also, if I clean everything else, would it be a bad idea to just put it back together, fire a round or two off, and let the gas pressure blow it loose?
     
  2. tnxdshooter

    tnxdshooter Member

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    Get some aerosol kano kroil penetrating oil and spray it liberally inside the gas tube. Let it suit for about 30 minutes and see if it doesn't come out then.
     
  3. ChaoSS

    ChaoSS Member

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    Ok, well, it's been soaking with some WD40 over night, so if it doesn't come out when I go at it again I'll look for something like that when I go down to the hardware store for some mineral spirits to finish cleaning everything up.
     
  4. trueg50

    trueg50 Member

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    Mine has the same issues if it gets dirty; the piston just doesn't want to fall out.

    I have a metal rod about the right size to fit down the side of the tube closest to the receiver, and tap out the piston.
     
  5. ChaoSS

    ChaoSS Member

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    Oh, btw, can someone explain the trigger group to me? Maybe when I have everything cleaned up and start putting it all back together it will make more sense, but I don't understand how the trigger actually does anything, pulling it doesn't seem to do anything but compress a spring? The guide I was following for disassembly says to make sure that it is cocked, and it should have been, as I pulled the bolt back and let it go forward before taking it all apart, but I don't really know.


    Also, as far as putting it all back together again, I keep reading that the coiled end of the spring is supposed to go forward, when I pulled it out it was the other way around. But, it seems to me that that shouldn't matter as much as putting it in so that the large and small recoil spring guides are in the right direction, but it doesn't say anything about that? So now I'm wondering if mine was just put together with that assembly in there backwards or if it really just doesn't matter which side of the spring is coiling up. When it isn't compressed the spring doesn't look any different either way, so I'm guessing that where it coils up is a matter of it coiling up over the smaller guide, not having room to coil over the larger one?
     
  6. greenlion

    greenlion Member

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    Kinky end of the spring toward the barrel. It may not make a difference, but why do it wrong if you don't have to. There are some good videos on youtube about the trigger group and the firing pins. Those would be more helpful than anything we could type here.
     
  7. ChaoSS

    ChaoSS Member

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    So that means small guide rod forward, right? I think mine was just put in backwards then.
     
  8. rust collector

    rust collector Member

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    SKS disassembly

    Piston should float freely in the gas tube. http://youtu.be/Iiq7Ey1-5eg

    Your original post sounded like you were working on the pin near the rear of the gas tube, which isn't necessary unless replacing the handguard on the tube.

    I hope the link helps. If the piston doesn't come out easily, there may be bigger problems.
     
  9. ChaoSS

    ChaoSS Member

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    No sir. I'm talking about the piston.

    It's still soaking in WD40. I got caught up in another project and don't like working on gun stuff with little parts with little kids running around the house. So, I'll see if it will come out a little bit later on tonight.
     
  10. JHansenAK47

    JHansenAK47 Member

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    Skinny retainer with the kinky end of the spring in the bolt carrier. You want the fat wide end out because it is a more stable base to put against the top cover and is less likely to walk, but IMO it isn't super critical.
    More than likely yes.

    I assume your trigger mechanism is out. In front of the hammer there is a lever that can be pushed down. It won't work all the way up or pushed all the way down that lever needs to be pushed just a little bit. On the left side of the trigger mechanism is a hole when you pull the trigger with that lever depressed you can see the feet on the transfer bar moving. If it is in the right spot the hammer will fall just make sure it isn't on your fingers.
    I would put mineral spirits in a bucket and submerge it overnight. It will clean the cosmoline out of the wood at the same time. I recommend boiling the metal parts and soaking the wood parts in mineral spirits. Don't boil the wood parts.
    I'm guessing you removed the piston tube by rotating the latch up. If you remove the piston tube then rotate that latch all the way up you can take the little piston under the rear sight out. If you read a good guide that would be in there but I am amazed at the number of people who don't know that it's there even after owning and cleaning an SKS for years.
     
  11. rust collector

    rust collector Member

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    If the cosmoline is holding it in, a bit of heat from a lamp or a hair dryer may help loosen things up.
     
  12. carbine85

    carbine85 Member

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    The piston is under spring pressure and held in place by the latch that holds the gas tube and hand guard assembly. I've never hand one get stuck. Are you sure you turned the latch far enough? It should fly out.
     
  13. carbine85

    carbine85 Member

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    The trigger allows the sear to move reward under spring pressure. There are some good youtube videos that explain it.
     
  14. tnxdshooter

    tnxdshooter Member

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    When are people going to learn wd40 is not a lube. It's a water displacer. Nothing more.
     
  15. tnxdshooter

    tnxdshooter Member

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    That's called the operating rod and it is under spring tension. Make sure you remove it really slow because if you just press it in and let it go it will go flying across the room.
     
  16. tnxdshooter

    tnxdshooter Member

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    The piston IS not under spring pressure. You are thinking of the op rod/gas piston extension. It's not the gas piston. Here you are giving misinformation to a newbie.
     
  17. ball3006

    ball3006 Member

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    Put down the wd40 and step, no run away. Do not put it on a gun. It dries and leaves a sticky residue. Use a gun cleaning solvent such as Hoppe's, etc. WHICH piston is stuck? A SKS has two pistons, one in the handguard and one under the rear sight. The piston under the sight is held in by the lever used to hold the handguard on. After you soak the piston with solvent, using a rod the size of the llittle hole in the handguard, drive the piston out. Then scrub the inside with a brush soaked in solvent. chris3
     
  18. ChaoSS

    ChaoSS Member

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    Just a note, I'm not talking about the piece that is under the rear sights. That one is out, no problems. I'm talking about the piston that is inside of the gas tube.

    [​IMG]


    This step right here.



    It's both. It isn't the greatest lubricant, but it is a passable penetrating lubricant that tends to not damage stuff. Maybe not the best thing for certain things, but it'll do for some stuff.

    Anyway, after I'm done I'm cleaning it all with mineral spirits. I didn't have any last night, so I didn't start with that step. Someone just said put the whole thing in the mineral spirits, I wasn't sure if that would damage the wood finish, but I'll just go shove the whole thing in there and let it have at it. The mineral spirits will clean up any WD40 residue as well.
     
  19. carbine85

    carbine85 Member

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    The piston is under spring pressure. You sir are providing misinformation. The rod and piston are 2 different parts. The OP original question was about the piston
     
  20. Miked7762

    Miked7762 Member

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    Is the gas tube original? I've seen more than a few aftermarket ones that were not properly fitted pinch the piston rod when the whole assembly was forced into place.

    The gas piston IS NOT UNDER SPRING PRESSURE. Read the other posts and look at the picture in the post immediately above yours. The piston floats freely in the gas tube.

    What you are describing is the operating rod, not the gas piston. The OP is asking about the piston.
     
  21. ChaoSS

    ChaoSS Member

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    Not according to the pictures I'm seeing. There is a piston and a piston extension. The piston extension is under the rear sights, and it is spring loaded. The piston itself is in the gas tube, and not spring loaded.

    Miked7762, I would assume that it is original. I am not entirely sure, honestly, I bought the gun from Classic Firearms online, and to my knowledge they aren't selling guns that have been messed with in America. Since the whole thing is coated in cosmoline, I'm assuming that it's in the same condition that it was in decades ago when it went into storage.
     
  22. ChaoSS

    ChaoSS Member

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    Ok, thanks for all your help people. I got tired of dealing with it and put the gun in the trash, where the piece of **** belongs.























    Ok, now that I gave everyone a heart attack, I'm just kidding. I pulled the tube out and used the smaller spring guide and a hammer to tap out the piston. It didn't take much effort and i don't see any rust or debris around the seal. Just about of gelled up Cosmoline. So now the stock and the receiver/barrel are in a plastic bag, hopefully melting out some of the gunk, and the rest is in some mineral spirits for a little while.


    Speaking of which, I forgot that I need to buy some better gun oil, but for now I have some stuff I got in a cheap cleaning kit, "Outers" gun oil, should I get something else before I put it all together? Or just a good dose of WD40? (I kid, I kid).
     
  23. tnxdshooter

    tnxdshooter Member

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    That wood be correct spring tensioned op rod/piston extension. Regular had piston is not
     
  24. tnxdshooter

    tnxdshooter Member

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    I told you for oil kano kroil is like brett heart. The best there is, the best there was, and the best there ever will be.
     
  25. ChaoSS

    ChaoSS Member

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    Thought the Kano was just for cleaning. My mistake. Forgot to look for it while I was out today, too much other BS to deal with with some other projects.

    Looks like I may have to order it online for now though so I guess I'll just go with what I have. It's not as if the SKS that difficult to tear down when you aren't dealing with the Cosmoline and decades of being gunked up.
     
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