Yugo SKS problems...


March 5, 2007, 05:40 PM
I recently acquired a Yugo SKS M59/66 with grenade launcher and spent some time shining it up. I went outside this evening to shoot it and ran into some problems. I found out that the shell doesn't eject even if the valve at the end of the gas tube is set to semi-auto fire. Then, I found out that the firing pin is a bit weak when shooting lower grade ammo. Remington shells shoot fine, but the cheap surplus stuff doesn't. Again, whenever it did shoot, the gas piston didn't function or something. The piston assembly isn't stuck and can be moved when disassembled. What's going on with it...?


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March 5, 2007, 06:26 PM
Sounds like 2 problems?

1. malfunctioning gas system - This is reportedly not uncommon with M59/66s. Will the rifle ever cycle correctly?
2. light strikes with harder (military) primers - Usually only cartridges with harder primers are recommended for the SKS because of the risks of slamfires otherwise. Will the ammunition exhibiting the problem work on a second strike? Will ammunition from the same lot work reliably in another rifle.

Don't know what to tell you about issue 1. Someone will come along with more knowledge than I.


March 5, 2007, 06:36 PM
The rifle didn't cylcle when the 3 Remington shells were shot through it, I had to manually cock after each shot. Then I tried 4 Hollowpoint Russian shells that did not fire after the 1st attempt. I did not try a second attempt, I don't like trying to refire ammo. I'm pretty sure the ammo will fire in my Chinese SKS, all the other ammo out of the same box did.

March 5, 2007, 06:51 PM
remove gas tube assembly

move gas shut-off to vetical and remove

take pipe cleaner and clean gas port

if this does not work see gunsmith

March 5, 2007, 07:00 PM
Are you sure you spent enough time cleaning the firing pin channel. It can get mighty gunky in there from all the cosmoline they use. It took me over a few hours per gun to clean three Yugo SKS's. Then when I decided on which i would keep, I had to clean it 2 or 3 more times to get out almost all of the cosmoline.

As for having the gas valve in the correct position, are you sure? I seem to remember seeing a diagram or picture somewhere on the Internet, where they said it was one way and they got it wrong. If you are sure it is set correctly, then take apart the rifle and clean it again. Cosomoline in the gas system is also a problem when you first get these. They are just wonderfully gunky.

All the best,
Glenn B

March 5, 2007, 07:35 PM
The gas valve may also just be corroded. SKSMan has replacements for $20 and Murray's has their own design for $25.

As far as gas valve position goes, vertical, allowing you to raise the grenade sight, is the non-cycling grenade launch position. For semi-auto cycling the valve should be turned down to the right, a position in which it will lock down the grenade sight.

March 5, 2007, 07:40 PM
Take the block in which the firing pin is located, and soak it in brake cleaner, nail polish remover, or some other heavy-duty degreaser.

I'm betting that you have Cosmoline clogged up in the firing pin, and its not letting it extend forward enough to strike the primers hard.

March 5, 2007, 08:56 PM
Yep the 59/66 is notorious for gas system issues, but luckily as others before me have posted it is a quick and easy fix. The problem is most likely in the gas valve, it is often corroded or worn down and does not seal properly, thus letting gas escape and not enough pressure to be released. Very common problem.

It is really cheap to fix, and super fast to replace (less than 1 minute) Here is a good description on the issue--


March 5, 2007, 09:10 PM
Hey--is your firing pin broken? If so if may still work on some rounds and be a slam fire risk. Have a look. This is the boat I'm in with mine. I cleaned it very well but couldn't get the bolt apart--so I cleaned as best I could with solvent/heat to remove the cosmo. Seems to be in 2/3 parts. Just a thought.

You seem to have a gas issue too. Murray is said to have a nice fix--I'm going that way on my prob I think.

March 5, 2007, 09:28 PM
When revitalizing a cosmoline queen SKS you should disassmble the bolt (http://www.surplusrifle.com/sks/boltdisassemble/index.asp) to thoroughly clean it. Frankly, I couldn't get the firing pin retaining pin out, so I used the method Grant48 recommended. When it is clean, you should be able to shake the bolt and hear the firing pin rattle around freely.

Eventually I sent it to Murray's, where it was disassembled and fitted with their firing pin and firing pin return spring.

March 5, 2007, 10:17 PM

Smokey Joe
March 5, 2007, 10:30 PM
I understand that Simonov's original design for the SKS included a firing pin return spring, but that it was eliminated as a cost-cutting measure. Gol-dang bureaucrats.

Anyhow, as the previous posters have more than adequately pointed out, there are fixes for both yr problems.

Enjoy the SKS. Given that it is in proper mechanical shape, it is a rugged, dependable weapon. No target gun, but one that always fires, ALWAYS, every time you pull the trigger.

BTW, don't go thinking that you need a big AK magazine for yours. The installed 10-round mag works really well with stripper clips. To use anything else is to invite a whole new set of problems.

March 6, 2007, 04:29 PM
Thanks for the advice, I know alot about the functioning of the SKS, but never messed with a Yugo. I noticed that my gas valve was corroded, therefore not ensuring a good seal. I'm going to get one machined out of Stainless Steel or Durarod, something hard and will resist corrosion. As for the Paper Clip remedy, I might try that just for the fun of it. Again, thanks for the advice and links, I was totally clueless. By the way, I'm getting pretty good at taking a SKS apart after this spell.

P.S.- Has anyone tried those new T-6 adjustable stocks for the SKS. I really like the looks and am wondering it they're worth $70.

March 6, 2007, 04:48 PM
1) No need to have a new gas valve custom machined- they're readily available online. www.sksman.com is a good place to do business.
2) Strip your bolt completely, and if the firing pin looks iffy, order new parts for it from sksman when you order the valve.
3) Don't bother with the T6 stock. Not that it isn't any good, but before you install it, you need to install a number of US made compliance parts and remove some evil features from your rifle (grenade launcher, bayonet, and night sights). It just isn't worth it. The time and money adds up in a hurry. If you want an inexpensive AK, just go buy a Romanian AK with the Tapco T6 stock and be done with it.

March 6, 2007, 10:10 PM
I've actually thought about an AK, but I just like the SKS for some reason. My grandfather gave me his Chinese SKS, so I want to keep it original. I got the Yugo and want to make a tatical/coyote rifle. The money to drop in it isn't an issue because I'm not gonna spend more than $150 on accessories. As for the machining on the gas port, it'll be free except for buying the material. I want a Stainless Steel reproduction to resist corrosion and for reliability. I'm getting more interested in assault rifles, the SKS is a cheap, reliable gun whenever you get it in operational form. I wasn't very familiar with the break down procedure. You all have been a big help and I'm sure that the gas valve is the problem after all the posts and links were taken in.


March 31, 2009, 09:49 AM
I have a yugo SKS that was shooter grade from AIM or SOG. I don't remember. However, Mine has tendency to FTE and the spent shell gets stuck half way out of the area and sticks the bolt open partially. Also, when it does shoot a mag-full the lever that holds the gas piston in place tends to creep upward to the point where the gas piston becomes loose. Is there a stronger spring or something to hold it in place? I am very discouraged with this rifle. I bought the tacti-cool folding stock which caused more problems and have had nothing but bad luck with aftermarket magazines. So its back to it's original form and still is jam-o-matic.:(

March 31, 2009, 04:10 PM
Has anyone tried those new T-6 adjustable stocks for the SKS. I really like the looks and am wondering it they're worth $70.
Well, those of us who actually admire the looks of the SKS will suggest you leave it the way they made it.


March 31, 2009, 05:25 PM
Well, those of us who actually admire the looks of the SKS will suggest you leave it the way they made it.

Especially if you bought it with a C&R license. BATF requires that they be left the way they were made. Plus they look better original. ;)

March 31, 2009, 06:24 PM
Buy a norinco or russian SKS. Problem fixed :neener:

March 31, 2009, 09:45 PM
Wow...this thread brings back some memories.

I got the rifle to fire, but only with Remington ammo and put a piece of paper clip to act as a gasket on the gas valve. It would work, but still needed some new parts that I didn't want to buy. The barrel was also more pitted than I thought, so I ended up trading it on my Stevens 200.

Actually bought another Norinco not too long ago. I love my SKS rifles, and after owning that Yugo I can strip one in the dark, blindfolded, and standing on my head I do believe.

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