SKS piston


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ChaoSS
October 13, 2013, 02:46 AM
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?

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tnxdshooter
October 13, 2013, 04:45 AM
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?

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.

ChaoSS
October 13, 2013, 08:34 AM
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.

trueg50
October 13, 2013, 08:41 AM
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.

ChaoSS
October 13, 2013, 08:59 AM
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?

greenlion
October 13, 2013, 09:28 AM
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.

ChaoSS
October 13, 2013, 09:39 AM
So that means small guide rod forward, right? I think mine was just put in backwards then.

rust collector
October 13, 2013, 03:23 PM
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.

ChaoSS
October 13, 2013, 03:36 PM
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.

JHansenAK47
October 13, 2013, 03:56 PM
So that means small guide rod forward, right? I think mine was just put in backwards then.
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.
Am I going to damage it if I just go at it with a nail set and a big hammer?
More than likely yes.

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
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.
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.
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.

rust collector
October 13, 2013, 03:57 PM
If the cosmoline is holding it in, a bit of heat from a lamp or a hair dryer may help loosen things up.

carbine85
October 13, 2013, 04:20 PM
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.

carbine85
October 13, 2013, 04:25 PM
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.
The trigger allows the sear to move reward under spring pressure. There are some good youtube videos that explain it.

tnxdshooter
October 13, 2013, 04:49 PM
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.

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

tnxdshooter
October 13, 2013, 04:50 PM
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.

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.

tnxdshooter
October 13, 2013, 04:52 PM
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.

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.

ball3006
October 13, 2013, 04:52 PM
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

ChaoSS
October 13, 2013, 04:53 PM
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.

http://www.surplusrifle.com/sks/carbine/graphics/l/20.jpg


This step right here.



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

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.

carbine85
October 13, 2013, 05:14 PM
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.
__________________
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

Miked7762
October 13, 2013, 05:32 PM
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 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

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.

ChaoSS
October 13, 2013, 05:54 PM
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
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.

ChaoSS
October 13, 2013, 06:12 PM
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).

tnxdshooter
October 13, 2013, 06:38 PM
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.

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

tnxdshooter
October 13, 2013, 06:40 PM
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).

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.

ChaoSS
October 13, 2013, 07:22 PM
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.

hang fire
October 14, 2013, 02:01 AM
If the SKS had been fired with milsurp ammo and not cleaned, or not correctly cleaned, (with water etc.) then piston may be corroded and froze in place.

tnxdshooter
October 14, 2013, 04:12 AM
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.

It's great at cutting through crud. It's also a decent lubricant. It will really break a frozen bolt loose.

ChaoSS
October 14, 2013, 11:52 AM
Well, the piston and the tube don't have the same numbers, and it seems that it was forced in. I'm sanding down on the piston a bit, and I got it to go back in, but it only goes down about half way. There's a little bit of an obstruction in the tube that I'm trying to sand out but it's not going too well, maybe I'll just sand down on the piston just a tiny bit more and see how it goes. I really don't want to have to buy a new tube/piston for the thing, although I guess I could get some parts that would contribute toward 922r compliance if I ever want a new stock for the thing.

Miked7762
October 16, 2013, 12:55 AM
The SKS uses a short stroke gas system and the piston travels less than an inch to the rear when firing. If it is making it halfway down the tube before sticking it is more than sufficient.

ChaoSS
October 16, 2013, 09:37 AM
Really? I figured that it had to travel at least as far as the little vent holes in the sides. How does it work then, just hits the bolt carrier hard enough to knock it back without having to actually push it back all the way I guess? I guess that makes sense though, the total length of the gas tube cylinder isn't long enough to push the bolt carrier all the way back.


Now I just want to take this thing out and play with it. I've dry fired it a number of times just cycling it through making sure everything was working and the firing pin wasn't getting stuck forward, so I figure that means I cleaned that up well enough. Now there's nothing left but to take her out and shoot some paper.

Miked7762
October 19, 2013, 07:39 PM
Yes, the operating rod strikes the bolt carrier and only inertia drives it back the rest of the way. The next time you have the gas tube out, push the operating rod back as far as it can go. That's all the movement the op rod and the gas piston have.

If you haven't completely disassembled the bolt to clean it I would recommend that you do so. It's easy to do and if there was enough cosmoline to cause the gas piston to stick there's definitely going to be some left on the bolt internals. I can tell you from experience that a slam fire isn't fun.

TimboKhan
October 26, 2013, 02:05 AM
Question asked and answered, but here is my two cents anyway:

Cosmoline removal is a PITA. I have de-cosmoed a few guns, and the best/least effort solution was one I got of the old surplusguns site: I built a simple lightbox and let the bulk of the crap cook off. An even easier, but functionally identical method, is to leave it outside in a metal garbage can in the middle of summer. Provided you have a area secure enough to do this, it works and requires virtually no effort in getting rid of the majority of the cosmoline. Mineral spirits do a pretty good job on whats left over. I have even tried the gasoline method suggested in book two of "The Corps" series. More or less I just wanted to see if it worked, and it did, but the book also didn't lie about how dangerous it is. I had no issues, but it's the only time I have ever felt unsafe cleaning a gun!

For the record, WD-40 is not a good lube, but it isn't a particularly good solvent either. Despite the "sticky residue" thing, my dad has done long-term storage on several guns for years and his only real trick is a liberal spraying down with WD-40 before they go in the case. All of those guns are in really, really good shape with none of this sticky residue. Not saying it's the greatest thing in the world, but the only empirical evidence I have to go off of suggests that it has it's place.

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