Hi all, I have been visiting this site for a long time and have found a lot of good information and very helpful members. I usually find the answer to my questions in here some place. I just registered because I finally have something to contribute.
I have two Yugo SKSs. One is in very good condition and shoots very well. The second one bought from a different source was in a very used condition. Cosmetically it is good, but has a lot of wear on the rifling and had a failure to cycle function problem. The gas valve was severely eroded. The gas piston and gas cylinder was pretty close dimensionally to my other SKS so I swapped the gas valve and that seemed to fix the problem. It would still fail to function once in a while but so did the good SKS.
I ordered a gas valve from Heddonpal. The valve I received was in much better condition than the worn out valve, but not as good as the valve in my good SKS. Now the action would cycle enough to stovepipe.
I figured that any replacement part I bought would be used so I decided I needed to find a way to fix it myself. I've read about the ball bearing flair mod but didn't have a ball bearing the right size. Most of the other options (machine a new gas valve) would cost more than the gun did in the first place.
After noodling the problem, I came to the conclusion that I needed a sealing ring. I took a regular paper clip and bent it around a drill bit slightly smaller in diameter than the countersink in the end of the gas cylinder and cut roughly to size. Then I put it in the countersunk area at the end of the gas cylinder.
I had a pretty large gap but thought I would try it anyway. (Sorry for the focus, I was hand holding the camera). It functioned flawlessly. I shot about 20 rounds to make sure and then went back the shop to make one with a smaller gap.
This is the final gas ring after about 100 rounds of Wolf. 100% flawless functioning. The gap in the ring is at the bottom. Sorry it's hard to see; I didn't clean it up before I took the picture.
This shows both gas rings. The one on the left is the prototype, the one on the right the final version.
I'm going to see how durable the paperclip wire is. I may end up switching to stainless safety wire; but my first impression is there is no erosion of the metal in the paper clip so I'll probably just leave it as is. Since it only takes about a minute to make the gas ring, if I had to do it everytime I shoot it, it's no big deal.
The only down side is you can't rotate the gas valve with the ring installed because it seals to the chamfer area of the gas valve and is an interference fit.