Trouble shooting SKS

[wonderwolf]

I got my Yugo SKS about 2 years ago and cut off the nade launcher,sight and all those other vestigial appliances we civilians don't need. ( I shot it first to make sure it worked...and well It didn't really) Anyways I replaced the gas shut off valve with a new one from gunpartscorp.com and it works for the most part now.


My friend just got his SKS about a month and a half ago and we went out to shoot it. He is a newb and wanted me to try it first. So I put two in the mag and racked it back. First one shot ok but the bolt didn't cycle. Ended up fliping the gun over and hitting it smartly against a 4x4 wood pillar to get it open and the next round chambered. shot that one and had to repeat the process from shot 1. I oiled it down and put 2 more rounds in. This time it allowed the bolt to come back a ways or let the case mouth of the fired round jam the bolt open on right above the barrel (read it didnt cycle the bolt all the way back). I changed the gas shut off valve with the one off of my rifle which is still in good condition. (his was very pitted and worn). Put 5 rounds in the mag after reassembly and went to town..the 1st shot cycled the bolt ok. but after that I had to rack the bolt back with the 4x4 wood pillar by our shooting bench.

What gives? I personally cleaned the gun in and out and made sure it had enough lube. I'm not that well versed in SKS I'm more of an AK guy myself. thanks for the help :afro1:

[wonderwolf]

Beuller..........Beuller.............Beuller






:catcorn:

[okie shooter]

Ok I will offer some suggestions, first, when you rack the rifle manually, does it seem to cycle ok, take out the recoil spring, and leave the top cover off. Watch and see if anything hangs or gets into any bind when pulling back the bolt and returning it. Compare it to the action of your rifle next to it. Thats where I would start.

Next I would pull the operateing rod(secondary gas linkage under the front site) make sure its free in its cylinder and slideing ok, then check the gas piston in the gas tube for the same. Make sure everything slides back and forth with no binding.

Make sure you clean the heck out of the chamber too, these have been shot with laquered sealed ammo, thus may have a varnish buildup there.

Above are just things to check, I would also suggest fireing the rifle as a single shot with the gas valve set not to cycle, see if the rifle binds up and needs the 2x4 to open the action, that would tell you if the gas system or operateing causes the problem or if the cases are swelling in an over sized chamber or something and locking the rifle shut. If the rifle can be operated as a bolt, with no problem you are getting some sort of binding in the bolt carrier/receiver. If the rifle operates as a single shot ok, I would be looking for problems in the gas system or something binding under high accleration that may not bind under hand operation.(something getting into a weird geometry when rapidly recoiling) really sloppy fitts between the moving parts and rails that when slowly moved seem ok but when rapidly moved might bind up.



Thats my two cents on your friends rifle affliction. Good luck.

[Geilt]

+1 to what Okie said. Shutting off the gas valve and essentially operating the SKS as a bolt action will tell you where the problem most likely is. Try operating the bolt manually without any rounds in it. Let it slam back in to battery hard. See if its binding up anwhere.

You may want to field strip it and check the recoil spring and guide rod. If they in backwards you can get weird results. While you're at it check the guide rod too and make sure its not bent.

Another possibility, albeit an unlikely one, is that you're using faulty ammo. Perhaps the powder got damp or you have iffy primers that aren't igniting the powered properly. Either could generate enough pressure to get the bullet through the barrel but still prevent enough pressure to build up to blow the bolt back sufficently.

Check the primer on a fired round. If the firing pin is puncturing the primer cap it could be venting needed gas away from the barrel. Like bad ammo, this could reduce the pressure enough to interfere with operation.

Also compare the brass on an unfired round. Does the fired cartridge have an glaring differences or gunk on it? If the brass is getting stuck in the chamber or only extracting partially you may find a hint to the underlying issue. This goes along with what Okie said about some having caked up chambers due to lacqured ammo being used.

[Jagman]

Sounds like a cosmolene problem causing the bolt to lock up, Maybe some cosmo leached out when if got fired?
clean it again and also you could check if the gas bypass hole under the gas shut off valve is not blocked, double check the firing pin will rattle when you shake the bolt, these are notorious for slam firing.
Jagman

[SteelCore]

If the top receiver cover shows internal wear, you migght be seeing the result of the top covr binding on the bolt carrier. look at the silver carrier for signs of wear.

There might also be some grit or something in the rails that the bolt carrier slides along...

It does not sound like a gas tube issue, since the problem is not the mechanism unlocking after shooting...I'd also check what Gelit recommends..."check the recoil spring and guide rod. If they in backwards you can get weird results."


Let us know what you find out, and we can go from there.

[wonderwolf]

LOL took mine apart and I did have the recoil spring and rod backwards his was oriented right though.....That would explain some stuff I guess...But still gonna try the new gas nut since his is pitted so bad.

[nevada]

Extra reading help here: www.simonov.net

[SteelCore]

:oops:

Also use the gas port cleaning tool (or those pipe cleaners with the bristles) to clean the gas port while you're in there. corrosion from hot gas and leftover powder is common there, don;t be surprise if it is a real pain to clean out.

I am always surprised at the amount of space around all the SKS gas piston and tube parts...it obviously just uses the initial gask 'kick' to drive the piston back.

[texgunner]

A friend and I both bought Yugo 59/66 a couple years ago from IO in "unissued" condition. Both of the guns did look to be brand-new. When we took them to our range though, my rifle would not cycle. We exchanged trigger groups; no change. We also swapped bolts; no change. After taking my rifle back home, I compared it to my '57 Norinco. It didn't take too long to see the difference, and the cause of the cycling problem. The receiver rail on the left side was not parallel with the receiver. The rail actually got wider as it got closer to the chamber. It was causing the bolt to move to the right, thereby binding when it closed. A few deft strokes with a file removed enough metal to restore it to the proper shape. The cycling problem was gone and the rifle has performed flawlessly ever since.

Here's a pic of the two Yugos we bought. Both had unfinished stocks, still rough to the touch. He did his with Chestnut Ridge Dark Walnut military stock stain, and I left mine in its natural state. Both were then finished with handrubbed coats of 1/3 each mixture of BLO, turpentine and beeswax. His on the left, mine on the right.

http://i7.photobucket.com/albums/y292/Texgunner/2yugosks.jpg