Chinese SKS will not eject cartridge

[mordaal]

A few weeks ago I was rummaging around in my barn and found a Chinese SKS I forgot I had ( SKS, can't have just one). So I cleaned it up and test fired a couple of blank rounds in it and it fired perfect, however using blanks does not have the power to eject the spent cartridge. So I moved on to the next step and fired a couple of real ammo and it still would not eject. I checked the small piston and spring and they are good I took the gas tube off and cleaned it, the long piston and cleaned the gas port with my Dremel using a small wire brush. Then I cleaned the hole going from the gas port into the rifle barrel with a tobacco pipe cleaner and solvent , ( or from the barrel to the gas port depending on how you look at it) and put everything back together. Confident that it would now function I tried firing it again, no joy  , it still would not eject the spent cartridge.
So I took the gas tube back off and tried 3 other different Chinese gas port hand guards, it still will not eject.
The only thing I can think to do is replace the gas port, however before I remove the FSB and replace the gas port am I missing something else that could be the problem?
Advice would be appreciated.

[7.62Hunter]

Possibly a bad extractor? Is your bolt coming back? Does it seem gassed enough?

[Groovy Mike]

Does it extract when you cycle the bolt manually?

[Rocketvapor]

WOW. I can't really think of a reason to remove the gas port.

[mordaal]

Possibly a bad extractor? Is your bolt coming back? Does it seem gassed enough?

The bolt will extract manually. It does not seem to be getting gassed enough to push the bolt carrier back.

[deano186]

Could the bolt and cover be restricted from moving back properly in the receiver?
Does it work okay by hand?

[Rocketvapor]

Pull the bolt and carrier back, let it lock into place with the bolt hold open tab, then take the gas tube off and use the piston to push the Op-rod (short piston) back by hand about 3/4 on an inch. 
You will pushing again the spring but bite down and push it back

[Old Outlaw]

First thing I would do is if you got a cleaning kit in the stock with it, use the gas port reamer/cleaning tool in that gas port. May be just old cosmoline or carbon build up. But this is why they issued that tool with every rifle.

[mordaal]

Pull the bolt and carrier back, let it lock into place with the bolt hold open tab, then take the gas tube off and use the piston to push the Op-rod (short piston) back by hand about 3/4 on an inch. 
You will pushing again the spring but bite down and push it back

I will give that a try today. And I have also used a copper wire brush cleaning tool to ream out the hole from the gas port to the rifle.

[Lake1025]

Before you do any additional cleaning of the gas tube verify you aren't losing pressure through the area around the piston first. You wouldn't want to be wire brushing it out so much that the pressure from each round is just blowing by. Follow instructions in this video:
https://www.youtube.com/watch?v=DrNigM7Wiuc

[J. Sotelo]

Hello  MORDAAL
I didn't see anyone ask, Is the spent cartridge stuck/hard to extract?
Can you pull the Carrier and Bolt back with ease?

Check the Chamber to ensure there's no corrosion, or build up.
Good luck.

[MuthaFunk]

I'm new to SKS' but could it be the carrier return spring is not mounted all the way to the rear of the carrier cover.  I saw a youtube assembly vid where the guy tucked the spring in ahead of the over then the cover didn't have any spring pressure on it when he pinned it place. 

Hope that made some sense. 

My thinking is it would possibly have the return spring over compressed possibly limiting travel. 

[Greatguns]

These are the general things to do and look at/for any time you have a cycling issue.
Make sure bolt and carrier travel completely and freely inside the receiver and cover.(not binding anywhere.)
Make sure your OP rod spring is not broken.
Make sure your recoil spring assembly is all present and correct, and installed the right direction.
Make sure your gas port is free and clear of any carbon build up. Not sure a pipe cleaner with CLP will remove the carbon build up. Get the actual gas port reamer tool or use a drill bit the correct size to clean out by hand. DON'T use a drill.
Check for carbon build up inside the gas tube and make sure the piston has full and free travel in it.
Remove bolt and inspect the extractor. Just because it will pull a non-discharged casing out by hand does not necessarily mean it will pull a discharged casing out in semi-mode. The extractor, if sufficiently worn can 'roll over' the rim of the casing. Especially if it is a combo of it being worn and the casing sticking in the chamber.
Check the extractor spring. It being worn out can also allow the extractor to 'roll over' the rim.
Also, check you casing for damage as well as the chamber. I had a sticky casing issue and realized the chamber has a gouge about 1/2" in parallel to the casing causing it to hang up. If clear then use a 20 gauge bore brush and thoroughly clean the chamber.

[mordaal]

Pull the bolt and carrier back, let it lock into place with the bolt hold open tab, then take the gas tube off and use the piston to push the Op-rod (short piston) back by hand about 3/4 on an inch. 
You will pushing again the spring but bite down and push it back

Tried your suggestion and the piston does push out about about 3/4 inch. I have also tried switching out the bolt and carrier with a couple others I have and it still will not eject. I have also tried several other dust covers with no effect.

[Lafayettegregory]

Is the gas piston extension in place? Its the small rod that looks like a gas piston inside the sight block behind the long shaft gas piston. The take down lever is on the gas block.