SKS Malfunction

[Flamingchicken]

The locking lever for the upper hand guard is not all the way down the piston might be binding

 

[Seven65]

Haha, I hope it's just that lever not being all the way down, that'd be a cheap fix.

Just gave it a really deep clean and made sure it was all the way down when I put it back together. I'll see how it does next time I'm at the range.

 

[Beermaker]

The locking lever for the upper hand guard is not all the way down the piston might be binding

Exactly. The gas tube assembly may be moving around. IF it's not the original tube you may have to do some tweaking to get it to lock down correctly.

 

[Skip4Play]

Bent gas tube guaranteed

 

[TRaTSeRiF]

Could also be a bent piston.. Once I dropped the piston on a tile floor and it started binding. Spent some time to try to straighten it out, but couldn't so I ended up getting a replacement.

 

[Seven65]

The flat spot should have a small indentation - this is where the hardness was checked after heat treatment. There will be one on the piston rod too. These are not defects.
Check the back of the gas tube where it was ground to fit at the rear sight - a burr on this surface is common.
In the stuck condition is the gas piston forward or is it also held rearward?

The piston is free when the extension rod is stuck. I can actually take the gas tube with the piston off and it stays stuck in that rearward position.

I think the metal on the inner edge of the extension rod is worn down and binding on the metal where the chamber steps down in size (where it's supposed to stop).

I'm going to try ordering a new rod.

 

[Beermaker]

Could also be a worn ot too short of a return spring for the OP rod. If you put the OP rod in with out the spring does it have loose clearence all the way through the OP rod "Chamber"? Did you have a look under the scope mount to make sure nothing in there was interfering with the OP rod movement?