SKS Type 56 Fix up!

Discussion in 'Technical Questions & Information' started by ShawnDow, Sep 12, 2012.

  1. ShawnDow

    ShawnDow Member

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    O.K. guys and or gals...
    I just acquired a SKS type 56 and if it matters its the Chinese version with the #26 inside a triangle. This is my first "gas operated" auto loader.. so.. I already asked about the cosmoline issue... that is soon to be resolved.

    My first question is geared towards the gas piston and gas tube "fit".

    I have noticed that the piston will not travel back into the tube to expose the vent ports. No the rod is not bent.

    Is the gas tube "tapered" or, am I hitting an obstruction (there are some ringed ridges about 1/2 inch before the ports) possibly the piston "chattering" in the tube, but they are minor. Can I scotch bright the heck out of the ridges? Is there a specific tool for cleaning this type of obstruction? Or do I get a new gas tube and piston set?

    Thanks for the input,
    Shawn
  2. Jim K

    Jim K New Member

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    First, the piston is not stopped by anything in the gas cylinder. It is stopped by the short-stroke piston extension in the rear sight base; it is that part that contacts the bolt carrier and it can only move so far. That will not be enough to let the piston contact the tapered part of the gas cylinder.

    Second, the holes in the gas cylinder are not to allow gas to escape but to allow air to escape and prevent it from cushioning the piston movement, so they are not, and don't need to be "exposed" when the gas pston moves back.

    Cleaning of the gas cylinder can be done with the normal cleaning gear, a rod and patches. Don't Scotchbrite anything.

    Jim
  3. ShawnDow

    ShawnDow Member

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    Hokey pokey! No scotch brite!:eek: I have a short stroke rod and spring on order... its missing this part... So I guess its not 100% all there... (I guess we can say it has a few loose screws, Kinda like me! :crazy:)
    Thanks for the info Jim K.
  4. JLA

    JLA Well-Known Member

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    you sure its missing? it doesnt reside in the gas tube with the piston rod. you flip the lever up and pull the upper handguard off which houses the gas piston and then continue flipping the lever over until it springs the tappet and spring out. That part resides underneath the rear sight base in itsw very own little bore.

    Heres a description of how it works..
    The hammer drops when the trigge ris pulled firing the chambered round. the bolt remains locked as the bullet begins to travel down the bore. As the bullet passes the gas port in the bore it shoots high pressure gas into the gas block which begins to drive the gas piston rearward. The gas piston thrusts rearward under high pressure and strikes the tappet under the rear sight base. The tappet begins to move rearward toward the bolt carrier under heavy spring tension which slows it down pretty quickly. the tappet then strikeds the bolt carrier with just enough force to get it moving, which is also just after the bullet exits the muzzle. the carrier slides rearward camming the bolt down at the rear and unlocks the breech and allows recoil forces to continue the cycling process of ejecting the spent round and chambering a new one from the magazine.

    It sound slike a loooong drawn out process but it happens in a split second. Its already happened and ready to fire again by the time you percieve the recoil of the shot.
    Last edited: Sep 12, 2012
  5. Jim K

    Jim K New Member

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    Hi, JLA, a couple of comments. The bolt is cammed up at the rear to unlock; it is cammed down into a recess in the receiver to lock when the bolt carrier goes forward. The recoiling force that continues the unlocking process is the inertia of the bolt carrier. Basically, it is the same process as in the FN Model 49 and the FAL, on a bit smaller scale, except those rifles have no intermediate tappet, the piston rod impinging directly on the bolt carrier.

    Jim
  6. ShawnDow

    ShawnDow Member

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    yep... the short rod and spring is missing... under the front sight.. day light! actually.. when the previous owners grand son took it apart a few years back .. I'm sure you guessed it. So new parts will be here friday! Thanks for the input guys... JLA..you could have made a movie with your explanation of the operating system. Very detailed. thank you again,
    Shawn
  7. ShawnDow

    ShawnDow Member

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    have any of you ever taken the trigger group apart o n the SKS? Im no dummy.. I must have weak fingers... what is the easiest way to get the hammer and spring off? Holy cow... my thumb hurts (hit it not just once.. but three times with the hammer) I was thinking about changing to the updated type spring group. If I smash my thumb again... its staying stock!
  8. Skipper

    Skipper Active Member

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  9. ShawnDow

    ShawnDow Member

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    O.K. thats what I tried doing in the first place... so.. just get a grip man! Ill tell ya' that takes some will power to pull apart. All clean now!
  10. ShawnDow

    ShawnDow Member

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    Time to sound really stupid!
    What is the difference between the Norinco SKS and the Chinese "26 in a triangle" SKS I have? Or are they they the same thing and I just don't know it?
    Shawn
  11. WHSmithIV

    WHSmithIV Well-Known Member

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