Gas piston stuck. How do I fix this?

[Railrider1920]

Hi folks,
This is actually my first post here. I've got a Yougo SKS with a grenade launcher on it. After the gun was shot, it was taken apart to be cleaned. It was put back together, but without the gas piston extension and spring.

The gun was shot a couple of times, each was just a single shot. I'm guessing the lack of the gas tube extension and spring changed it to a single shot instead of a semi-auto. It's
been sitting in a closet for about 4-5 years since that happened.
Now the upper hand guard/gas piston won't come off the rifle.

I'm the new owner.  I'm guessing when it was fired without the extension and spring, the gasses forced the end of the gas piston into the hole where the extension is supposed to be. Now I think it is stuck there, causing the upper hand guard to not come off.

Any idea how I can get this fixed? I thought about putting a rod into where the piston extension goes(the opposite end, above were bullet goes, second pic) and tapping on it with a hammer. Maybe heat up the area where the hand guard catch is and then tap on the rod (1st pic)? Any ideas?
Thanks,
Rob





image uploader

[Phosphorus32]

Welcome!

Yes, I bought a similar malfunctioning SKS once. Get a steel rod of a diameter that’ll fit inside the tunnel for the op rod, place the muzzle end down on a scrap 2x4 on a concrete surface. Spray some lube inside the operating rod tunnel, insert the scrap steel rod, and hit it with a hammer. It may require some stout pounding to dislodge the gas piston.

[Bob_The_Student]

That's what I would've done. Did it work?

[Railrider1920]

Thanks guys. Haven't tried it yet. I'll have to look around for a good rod to try this with.

[Fooey]

gunsmith, these rifles ain't $69.95 anymore.

[running-man]

P32's advice is spot on.  It's clear the op-rod is missing in your photos.  The first shot w/o the op-rod allowed the piston to travel much farther than then 3/4" required during normal operation  and likely press fit the head of that gas piston securely within the gas tube.  As such, it's going to take a bit of force to get it back out.  You should be able to mark the rod you insert into the op-rod hole with a simple sharpie mark and be able to gauge your progress.  You'll know immediately when it lets go as that rod will travel >1".

If you get zero progress after giving it the business with your hammer, that would be when it's time to reassess whether you need a professional to look at it.   

[Greatguns]

It could be the extension rod broke and the stem part fell out the back(or flew out the back). It is also possible the piston end is bent. I have had that be the situation on 2 different occasions, once with a Russian and once on a Chinese.  I had to remove the rear sight leaf and flat spring so I could get to it from the top to straighten the piston out enough to push it forward in order to get the piston and tube out. Had to replace the piston extension rod and spring, but the gas tube survived fortunately as it was EP'd matching.

[running-man]

It could be the extension rod broke and the stem part fell out the back(or flew out the back). It is also possible the piston end is bent. I have had that be the situation on 2 different occasions, once with a Russian and once on a Chinese.  I had to remove the rear sight leaf and flat spring so I could get to it from the top to straighten the piston out enough to push it forward in order to get the piston and tube out. Had to replace the piston extension rod and spring, but the gas tube survived fortunately as it was EP'd matching.

Very true, but man that's a crazy way for that part to fail.  It's just a turned down piece of round bar stock for Pete's sake, how could they screw that one up?!!  Good advice there though, removal of the RSL and spring will show a 'window' where you can actually see down into the op-rod channel and tell what's going on in there, even if you can't take off the gas tube. 

[Greatguns]

I've seen this happen before, as I mentioned. Usually the extension rod spring either gets weak and/or it breaks. Then there is minimal or no buffer when the gas pushes the piston back which produces an over extension on both parts as well as possible sticking. This in turn causes the rod and piston to be returned to position by impact of the bolt carrier instead of the spring causing the return. This in turn puts excess stress on the rod head and the piston stem and if not caught in time can ruin the cavity of the RSB where the rod sits.
The one instance I mentioned previously is probably the most severe I have ever seen in person.

[Railrider1920]

Thanks for the additional replies and suggestions.

I found a long screwdriver that fit well. I got the piston dislodged and out. I got the  spring and extension put in, the the gas piston and hand guard put back in place. Now the lock lever won't go back down into place.....

Pic is of the end of the piston that was lodged in place. Boy it's nasty looking lol.
Thanks again!

[Phosphorus32]

Since it's all aftermarket stock and handguard components, the ferrule has been removed and a new rivet installed (hopefully). The fit of the rear ferrule around the gas system takedown lever could be off. Looking at the lever from the right side, it should be at about 75 degrees (i.e. pointed slightly aft) when the operating rod and spring are tucked away, then the handguard/gas tube/gas piston assembly should be put into place gas block engaged first, then the rear ferrule end of the gas tube/handguard pushed down past the camming arm of the gas system takedown lever. Are you good to this point? Up to, or past, this point are where clearance issues should be apparent. If the rivet head isn't flush, it can interfere with getting the gas tube fully down, if the top of the rear ferrule is a bit square or jagged, it may not clear the camming arm of the takedown lever. Without pictures of the situation, this is the best I can do for a start.

[running-man]

I've seen this happen before, as I mentioned. Usually the extension rod spring either gets weak and/or it breaks. Then there is minimal or no buffer when the gas pushes the piston back which produces an over extension on both parts as well as possible sticking. This in turn causes the rod and piston to be returned to position by impact of the bolt carrier instead of the spring causing the return. This in turn puts excess stress on the rod head and the piston stem and if not caught in time can ruin the cavity of the RSB where the rod sits.
The one instance I mentioned previously is probably the most severe I have ever seen in person.

Good stuff GG.  I guess the jackhammeing you describe is indeed a pretty rough ride!  I hadn't thought of a spring failure combined with continued use of the carbine.  I guess even Simonov himself couldn't think of everything.


Railrider, I would suggest you reassemble in steps to see where the fitment issue might be: 

1) Does the op rod fit in there w/o the spring and no gas tube/piston and the lever turn down fully to locked?
2) Does the op rod + spring fit in there with no gas tube/piston and the lever turn down fully to locked?
3) Does the empty gas tube fit in place (with no op rod, spring or piston) and the lever turn down to locked?
4) Does the gas tube fit in place with the op rod & spring (no gas piston) and the lever turn down to locked? (Be careful with this config when you take it off again to not open the lever too far, the op-rod can shoot into the gas tube and get stuck and then you have a stuck gas tube with no really easy way to get it back apart...ask me how I know this).

Definitely check the ferrule rivet head like P32 says.  That causes problems when the head is mismatched or the rivet tail has not been expanded enough or ground flush.  Also check that the handguard length is good and you're not too long to fit comfortably between the gas block and rear sight block.

One final thing to check is that the top angle of the ferrule is correct.  I had a Sino-Banian that had a mismatched replacement gas tube.  When I got it the lever was stuck about 30° from full locked.  No matter what I tried, it just wouldn't lock up.  I finally put the gas tube on w/o anything inside and still couldn't get it to lock up.  I took a small file and took off just a little bit of metal on the angled portion, and it fit perfectly.  (That gun is still my favorite Sino-Banian BTW) 

[Greatguns]

If there is play in the rear ferrule where the top of it rocks forwards and backwards you might try, with a flat blade screw drive, gently pushing rearward and downward on the ferrule to see if that allows the lever to continue travel down into position. I have experienced many gas tube assemblies, where the HG has been replaced and the ferrule has play in it, that when the lever is pushed to lock it takes the ferrule out of position at the cam and makes it hard to close. Rocking the ferrule back and down fixes the issue usually.

[Railrider1920]

Again, thank you to everyone. Short answer, it's now in place correctly.

In the first pic, where the red arrow is pointing, is that the Ferrell mentioned in posts above? Where the blue line is, the metal was sharp to the touch. Also red line in second pic. I used a file and got those areas smoothed down. I also tapped it "into place" lightly with a hammer. I tried it without the piston and it fit. Put both rods in it and got it to the closed position.



In this second picture, the left side where the red line is, is kind of wrapped around the metal. The area with the blue line next to it is left straight up. It is now fitting in the gun all right so I'll probably leave it alone, but how should this area be? It looks like it was designed to be left straight like the blue line instead of wrapped like the red line.

In a slightly OT question, is the following pic the gas block? Red line is where it is now. Moved to the green line brings out a "bushing". Right now with the handguard gas piston assembly in place, it won't move to where the green line is. It will however move to where the blue line is. Is this used when firing a grenade? Should it be in a particular position to use it in semi-auto?

[Greatguns]

Glad you got it figured out Railrider1920. To answer your questions;
1) Yes that is the rear ferrule. The front ferrule is at the other end of the HG and consists of an upper and lower both of which are fixed. Also yes a burred ferrule can cause issues with the ever closing so your filing it was good. Never want to take off too much though.
2) Yes they are designed to be straight, but see them bent over all the time. Especially on gas tubes where the OEM HG has been swapped out for an aftermarket one like yours has.
3) Yes that is the gas block on an Yugoslavian M59/66A1. It is different than any other SKS gas block. The part that comes out when in the green position is a positioning button and the green position is for removing the gas valve for maintenance and/or replacement(they go bad with time)
When in the 12 O'clock position(red position) that shuts off the gas system for use with a grenade launcher. It can also be used if you are using brass cased ammo and want to save your casings without having to chase them down. The blue position is for semi-auto mode and the normal position it should be in.

FYI, if the gas valve goes bad, IE leaks gas from corrosion over time, it will cause gas to leak out around the gas tube lip and you will get short cycling of the bolt assembly and "stovepiping" effect with your ammo.

[firstchoice]

Again, thank you to everyone. Short answer, it's now in place correctly.

In the first pic, where the red arrow is pointing, is that the Ferrell mentioned in posts above? Where the blue line is, the metal was sharp to the touch. Also red line in second pic. I used a file and got those areas smoothed down. I also tapped it "into place" lightly with a hammer. I tried it without the piston and it fit. Put both rods in it and got it to the closed position.



In this second picture, the left side where the red line is, is kind of wrapped around the metal. The area with the blue line next to it is left straight up. It is now fitting in the gun all right so I'll probably leave it alone, but how should this area be? It looks like it was designed to be left straight like the blue line instead of wrapped like the red line.

In a slightly OT question, is the following pic the gas block? Red line is where it is now. Moved to the green line brings out a "bushing". Right now with the hand guard gas piston assembly in place, it won't move to where the green line is. It will however move to where the blue line is. Is this used when firing a grenade? Should it be in a particular position to use it in semi-auto?

Not sure what happened to your pics, Railrider1920?

firstchoice