gas cut-off on Yugoslav SKS's


December 27, 2003, 05:52 PM
These are the short rifles/carbines with the grenade launcher tube attached, and folding knife bayonet.

Looking down at the top of the gas block, one sees a figure 8 type cut, upper hole smaller than lower. There is a "button", it's moveable, that as the rifle came, rests against the grenade sight, in it's folded down position. The button must be moved into the figure 8 cut in order to raise the grenade sight.

I assumed that the gas system would be shut off when firing grenades, but have been told that a "ball round" was used to launch rifle grenades, which seemingly would obviate a gas cut-off.

Anyone know about this? Possibly, this button might allow removal of some part from the gas block for cleaning? Appreciate any information. Thanks.

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December 27, 2003, 06:41 PM
I assumed that the gas system would be shut off when firing grenades, but have been told that a "ball round" was used to launch rifle grenades, which seemingly would obviate a gas cut-off.

DON'T try lauching grenades with anything except GL blanks only.

The button is indeed the gas shut off valve for launching grenades.
You're set for normal semi-auto operation when it's over to the side and blocking the GL sight from being raised.

To use the GL launcher:

1. attach a NATO spec launching adaptor w/grenade to the spigot
2. push down on the button on the gas block and move it to the center
3. raise the GL sight
4. load a single blank round
5. aim
6. fire

Cycle the action manually to eject the spent blank.

The button has nothing to do with cleaning or removing the gas block.

Here's a copy of the CTD SKS manual in .pdf format (

Have fun. These Yugo's are a blast. :)

December 27, 2003, 07:17 PM

thanks so much for the information/confirmation, including the manual. perhaps I will be able to assist you one day, who knows.

thanks again, and happy holidays.

By the way, the cosmoline, or "yak fat" preservative that they used seems particularly tenacious, compared to some preservatives that I have contact with over the years. perhaps I'm just getting old.

December 27, 2003, 08:02 PM
No, you're not getting old (but then, I haven't seen ya :D ), the cosmoline in my Yugo took more than one round of cleaning to fully remove. Tenacious stuff.

December 27, 2003, 08:59 PM
Alan, if you want to remove the gas valve, remove the hanguard assembly. Then turn the gas block button to the up position. Now slide it rearward. When it gets to the rear position the button will come off along with a spring. You can now pull out the gas valve for cleaning. Mark

December 27, 2003, 10:31 PM
DON'T try lauching grenades with anything except GL blanks only.
and don't place the butt of the rifle on your thigh like John Wayne when you fire it unless you want to walk like him for the rest of your life. :neener:

December 27, 2003, 11:18 PM
To all who replied to my question (s) about the Yugoslav SKS rifle, jimpeel, railroader, raistlin and last but not least, glocksman, thanks for your thoughts, time and trouble.

Thinking about it, it might be interesting to fire some exercise (dummy) grenades. Question is, where does one get the dummies, the "blank"rounds, and such other bits and pieces as might be necessary? I suspect that the firing of rifle grenades is simply another of life's small but interesting pleasures that I will have to go through life, not having experienced.

The particular example that I got, from the ads I've seen, seems typical of the genre, and appears to be a well made piece, just about the entire thing appears to be forged and machined, magazine excepted, serial numbers, including the stock, all match, more interesting for a collector than for a shooter, and dry firing a couple of times, the trigger feels quite good for an "obsolete" military rifle. We shall see. Thanks again gentlemen.

December 28, 2003, 12:11 AM
Did a Copernic search on "sks grenade launcher blanks" and got some interesting results. 7.62X39 Blanks, 100rds 20.00

December 28, 2003, 02:39 AM
There were a whole ton of nato-spec dummy grenades in launching cradles around awhile back. I believe they were all US surplus. It hink they ran 5 bucks a piece or something like that. And just to reemphasize a point already made, using a ball round to launch grenades is a good way to end up in a hospital (or morgue).

February 3, 2004, 07:47 PM
Finally got a break in the weather yesterday, lots of snow on the range, but it was "mild" so out I went with 100 rounds of Rissian "Service Ammunition", to zero the rifle and play a little.

The thing fed ammunition, fired, extracted and ejected fired cases properly. I suppose that it will take a little getting used to, especially since I haven't fired rifles much recently nor service rifles for many years.

One thing noticed is the following. Rifle is supposed to lock open, after last shot in magazine is fired, but doesn't. Cycling the action manually, the action does lock open. Cannot see anything obviously out of wack, nothing "bent, missing or broken", so far as I can tell. Anyone have any ideas, suggestions or whatever?


February 3, 2004, 09:45 PM
Check the bolt lock for free movement. Spray it out with a non-residual cleaner. Remove the trigger group before you spray it or be prepared to re-lubricate it.

Also check the tab on the follower of the magazine to see if it is bent, binding, or if the follower arm spring has lost tension.

The follower is also supposed to freely rotate on the follower arm.

Also check the follower for free movement within the magazine. Make sure the tab on the follower is not rubbing against the side of the trough in the magazine frame.

Greg L
February 3, 2004, 10:42 PM
Thinking about it, it might be interesting to fire some exercise (dummy) grenades.

Just think of it as 200 meter lawn darts :D . I always thought that it would be fun to get a couple of lunatics (well one other one anyway ;) ) & stand on opposite sides of a big field & launch them back & forth at each other. As long as you were paying attention (& using the blue grenades :eek: ) & standing a bit off to the side, it shouldn't be that big of a safety issue. Certainly would beat hiking all the way across the field to get your one grenade because you were too stupid to buy more than one :rolleyes: .


February 3, 2004, 11:48 PM
There have been rifle grenades designed to be fired with standard ammo. Most of them use a bullet trap, but I believe FN produced one that let the bullet pass through the grenade.

February 4, 2004, 12:42 AM

You are well and truly a source of endlessly interesting tid-bits.

I just read through your comments, and all that you mentioned appears to be in order, except for one thing.

When one pulls the operating handle to the rear, the bolt and bolt carrier lock to the rear, allowing the magazine to be charged using strippers or with single rounds.

I take it that the "bolt lock" you mentioned is a piece of steel, that slides vertically and engages the bolt at 6 oclock position, locking same to the rear. When I depress the magazine follower, this piece drops, but seems to move slugishly.

I take it that this is the part you speak of, referencing your mention of spraying with a non-residual cleaner, how about either lighter fluid or aerosol brake parts cleaner?

Re lubrication of the trigger group, the entire unit was pretty much loaded with cosmoline when I got it, as was the rest of the rifle. I decosmolined it with gasoline, then lubed parts of the trigger group I could reach, the main spring, with Kellube M12, a synthetic gun lubricant, that seems to work well with semi-automatic pistols.It's the lighter version of Kellube.

Thanks for the information/suggestions.

February 4, 2004, 12:50 AM

I believe there is/was a Polish service weapon, selective fire I suppose, that launched grenades with ball rounds, rather than blanks.

Can't swear to that though.

February 4, 2004, 03:23 AM
Okay, the bolt lock is the problem. When you charge it by hand, you pull it back and it is in the tenths of seconds or more before you release it. When firing, however, the bolt is back for milliseconds.

If the bolt lock is sluggish going down, it is just as sluggish coming up. It likely has cosmoline in the ways and behind it.

Lighter fluid should clean it out. Simply disassemble the trigger group and bolt group (so you don't get a bad case of M-1 thumb) and spray it out while exercising it. It should move nearly friction free when you are done.

Also, make sure the firing pin is cleaned out fastidiously. Do not oil or lube the firing pin in the carrier. It gets gooped up with dust and debris and causes slamfires when the firing pin sticks in the forward position. There is no spring to return the firing pin to its at-rest position; but there are aftermarket kits that you can buy that places a spring in the group to pull it back and avoid slamfires.

February 4, 2004, 11:49 AM

As I said in an earlier post, you are an endless source of interesting tidbits, that is a compliment, in case you had any doubts. More important is your WILLINGNESS to share same, taking the time to respond to what might be the odd DUMB QUESTION.

If memory serves, in earlier models of the SKS, Russian I believe, there was a retractor spring on the firing pin, sort of similar to that on some Browning designed pistols I suppose. The return spring was eliminated along the way, an "economy" move perhaps. Of course neither the M-1 nor the M-14 had retractor springs, though they were of a different design. Also, there are differences in firing pins, as I understand.

I have seen cautions re the need for the pin to SLOP AROUND IN THE BOLT of SKS's, same with the AK-47 I believe. Grease, dirt or corrosion could cause the thing to hang up FORWARD, which can cause slam fires. at least an annoying situation. I will squirt the bolt with lighter fluid every time I clean the rifle, usually after firing. As for aftermarket parts, the spring you mentioned, If It Ain't Broke, Don't Fix It comes to mind, just pay attention.

Your mention of M-1 Thumb brings back memories. I shot one for years in competition, LEFT HANDED YET, and never caught my thumb, saw it happen once I think, looked painful. With the SKS, looks like the bolt and carrier assembly are heavier than the M-1 bolt was, likely hitting harder. Who knows, but that one of these days, we will bve reading articles about the latest firearms related problem "SKS THUMB", especially if enough of these rifles come into people's hands.

Thanks again.


February 5, 2004, 02:16 PM
Thanks for the kudos. There are no "dumb quesions" only dumb mistakes.

You won't know the success of the cleaning effort until you shoot it again but I am willing to bet that the problem will disappear.

Here is a site on the removal of the firing pin, cautions on replacement, pictures of the various types of firing pins, and a video of how to remove the pin.

February 5, 2004, 05:24 PM

Cleaned the bolt lock by squirting lighter fluid into, on to and around the sliding element. This seems to have freed things up, though as you noted, can't tell for sure till I fire it again, perhaps this weekend.

As to the illustrations of firing pins in the material you linked, interesting articles, the pin in my rifle, based on examining what can be seen of front and back ends, with pin inside the bolt, it looks like either the type 1 or 2 Chinese. One might have expected the Russian type, but given that Tito and the Russians were known to have "problems" who can tell. Haven't
taken the bolt apart, as I'm a bit leary about taking things apart, when one has to drive pins out, unless disassembly is essential.

The accuracy comments are interesting. I got really tight groups at 25 yards, firing over a rest, slightly larger at 50 yards, and put 5 shots into a standard IPSC target at 100 yards, three of the five would likely have hit a human of average size, this was with Russian "mil spec" ammunition from AIM Surplus, stuff comes in 700 round metal cans. I'm not really sure about my "old eyes" behind the relatively crude sights on this rifle, and then the trigger is quite heavy too. Barrel looks quite good, not "dark" and no visible blemishes or pitting. Might be me or the ammunition. Might try some of that Federal stuff, or bum some handloads. Haven't got dies or reloadable brass for this caliber. May not bother either, we shall see.

Anyhow, the rifle functioned without a hitch, I fired 60 rounds. What discernable recoil there was should hardly bother anyone. I suspect that the "problem" with action hold open after last shot, was, as you suggested, grease remaining there it shouldn't be, causing sluggish movement. We shall see. I have more lighter fluid, if it turns out to be needed. Also relubed, with Kellube, the trigger group, a little on the springs and a drop or two in pins. Shouldn't hurt, and might help. Can always send it out for rework.

February 12, 2004, 05:51 PM

The fix you suggested, re bolt not locking open at last shot, worked. Today was a bit warmer, and got out to shoot a little.

The "v" notch rear and small round post front sight play hell with old eyes. I believe that a peep sight rear, and a sharp edged rectangular front post, ala what I recall of the M-1 and M-14 rifles would help a lot.

Might try the sight set offered by Williams Gunsight Co. If they do not work, the original components can be replaced.

February 12, 2004, 06:54 PM
Great news.

Here's to good shooting and tight groups!

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