I'm still having problems with the SKS

polymerase2 · Post by **polymerase2** » Mon Sep 19, 2011 8:56 am

After fixing the firing pin retaining pin. It worked for 8 or more rounds then I had the same problem.
The firing pin is not hanging up this time.

I am getting misfires. When it misfires the primer is dimpled somewhat. The bolt does not want to retract. It takes some serious pulling.

This is an unissued Yugo. When I first cleaned it I was able to shoot about 100 rounds with not trouble or misfire.

The firing pin was the trouble the first time but I don't think it is this time.It moves freely in the bolt.
What seems the most obvious is the bolt is almost closing. If the bolt is not completely closed I suspect the hammer can drop but not get the full movement of the firing pin because the bolt is back a little.
Do you know if the hammer doesn't completely fall, is there resistance to recocking?

First theory: I suspect something is interfering with the forward movement of the bolt or bolt carrier.
Second theory, check the chamber for something that is preventing the complete seating of the round.
Is it possible to install any of the components of the bolt carrier spring backwards?
I have tried several different types of Wolf ammo. Could the lacquer be giving me sort of a reverse sticky bolt?

martin08 · Post by **martin08** » Mon Sep 19, 2011 9:05 am

Unless the bolt is in full battery, the disconnector will not allow the trigger bar to contact the sear. In other words, if the hammer drops, then it is in battery.

Now, since I don't have the initial story, how was it that the firing pin retainer was diagnosed? And how was it repaired?

Also, have you scrubbed the chamber? Have you removed the sear and cleaned the side grooves? Cleaned the inside rails on the sear travel area?

I know, a lot of questions. There are a lot of factors to consider with your symptoms. But we'll get it firing and cycling soon.

desdem12 · Post by **desdem12** » Mon Sep 19, 2011 9:43 am

I use laquered wolf all of the time so i dont think that is the problem. You should show the old pic of your bolt and maybe martin will have an answer.

polymerase2 · Post by **polymerase2** » Mon Sep 19, 2011 5:23 pm

I diassembled the bolt and the firing pin retainer looked like it had been peened. I assumed soft metal. Replaced with a new one.Firing pin looked fine.
I appreciate the comment about the hammer will not release until in battery. that was one of my suspicions and a big worry.
I am going to polish the firing pin and using a wooden Q-tip and some Tripoli try to make sure the inside of the bolt is smooth as well. Also make sure it is completely dry. Could I have a bent firing pin?
I will check the chamber and the sear. I was going to wait till 200 rounds to work over the trigger and change to the Wolff springs.
Don't worry, to me work means some very light polishing with 2000 grit sandpaper flued to a popsickle stick, followed by metal polish on the obvious wear points.
What is hard to figure out is the first 100 or so rounds were flawless. Not a single FTF.

Post by **Longcolt44** » Mon Sep 19, 2011 5:42 pm

Just a thought but have you checked the gas piston and asembly to make sure everything is clean and not full of smutz?

polymerase2 · Post by **polymerase2** » Mon Sep 19, 2011 5:49 pm

I just cleaned it before the trouble.

martin08 · Post by **martin08** » Mon Sep 19, 2011 7:52 pm

Yes, Yugo firing pins can be a bit soft compared to others. But it usually takes a pierced primer to damage them. If your pin has no visible scarring/galling on the retainer stops, then it should be OK. Also, is the firing pin installed right side up?

Take a good look at the outside end of the retainer. Is it working its way out and contacting the receiver wall? If so, it can cause the bolt to be misaligned, and also create the difficulty extracting the mis-fired round. A couple of light prick punches on the retainer pin shaft will ensure that it will stay put.

Another common factor of your symptom is a bolt that is too long, and locks down against the rear bolt lug. This usually only happens when a bolt number does not match the receiver number, though. As yours was unissued, it should be matched and fitted for length and headspace at the arsenal.

I'm leaning toward the firing pin retainer... let us know.

desdem12 · Post by **desdem12** » Mon Sep 19, 2011 7:54 pm

Did you roll the firing pin to see if it was out of round? Some times the firing pin chamber is all rusted up inside as you're no supposed to oil it. You can ordere a firing pin with a spring from that place i told you about, i don't think they are much and he is pretty fast service wise.(unless hunting, his words)

polymerase2 · Post by **polymerase2** » Tue Sep 20, 2011 8:33 am

martin08 wrote:Yes, Yugo firing pins can be a bit soft compared to others. But it usually takes a pierced primer to damage them. If your pin has no visible scarring/galling on the retainer stops, then it should be OK. Also, is the firing pin installed right side up?

Firing pin is correct. I can move it after assembly.Take a good look at the outside end of the retainer. Is it working its way out and contacting the receiver wall? If so, it can cause the bolt to be misaligned, and also create the difficulty extracting the mis-fired round. A couple of light prick punches on the retainer pin shaft will ensure that it will stay put.

I did notice that the retaining pin seemed to not fit as well as it should. I will look at the receiver and see if I can find any scuffing. I will also roll the firing pin to be sure it isn't bent as reccommended by Desdem.

Another common factor of your symptom is a bolt that is too long, and locks down against the rear bolt lug. This usually only happens when a bolt number does not match the receiver number, though. As yours was unissued, it should be matched and fitted for length and headspace at the arsenal.

I'm leaning toward the firing pin retainer... let us know.

I suspect that that is part of the problem. I also think the firing pin is getting partially stuck in the rearward position, which would absorb some of the hammer force. As I learned in the past, the thermostat and the fan relay can both go out at the same time on a car.

martin08 · Post by **martin08** » Tue Sep 20, 2011 9:00 am

Very true.

It can never hurt to upgrade the firing pin. The springed pins are just fine, or a hardened replacement (Russian, Chinese, Romanian). For some reason, the Yugo pins that you find nearly everywhere are of a softer alloy, and can lead to more failures down the road - albeit hundreds or thousands of rounds later. The bolt faces on Yugos also are prone to what is called the Volcano effect, where a circular ridge develops abutting the primer seat from the casings. A little stoning usually takes care of this, and lessens the chance for pierced primers, and light strikes.

After a pin upgrade, my thoughts return to the firing pin retainer as your primary concern. Any time a problem crops up right after a procedure, I always go back to the mechanics of the repair first, before delving too deeply into other possibilities. Make sure the new retainer is not contacting the receiver.

Now, on Wolf spring kits? Don't get me started!!!

polymerase2 · Post by **polymerase2** » Thu Sep 22, 2011 12:38 pm

How about a short start on Wolf springs. When I first shot the Yugo, the trigger was very hard and gritty, (I had cleaned but not disassembled the trigger assembly). I decided to break it in with a couple of hundred rounds before trying anything. I was going to lightly polish and change the springs. Am I heading for trouble? By the way, saw the SKS collection on the other thread, really nice and unique.

martin08 · Post by **martin08** » Thu Sep 22, 2011 1:43 pm

The gritty trigger can be addressed with a polishing of the sear and housing rails.

And lighter springs, especially the hammer, mean lighter primer strikes. Many misfire problems arise after installation of Wolf spring kits.

entropy · Post by **entropy** » Sun Nov 13, 2011 2:30 pm

If the firing pin is inserted upside down it will cause what you described. Ask me how I know this.

After being inserted upside down, it will be bent. replacing it (with a Chinese one) and the retaining pin is the best fix.

OLD OUTLAW · Post by **OLD OUTLAW** » Mon Nov 21, 2011 9:21 pm

The new firing pin retainer you put in. Is it specifically made for a Yugo rifle?
The Yugos have a different dimension than any others do. All other pins are a smaller dia. shaft and the head is a little different.
That pin can move on you or the head may not allow free movement. Wrong retainer can cause the symptoms you describe.
Martin described it earlier.

polymerase2 · Post by **polymerase2** » Sat Nov 26, 2011 9:14 pm

I've been playing with other guns and the Yugo is in the back of the safe for a while. So far, I did notice that the new retaining pin is a bit loose, I very lightly oiled the firing pin so before I do anything I am going to clean everything with alcohol and try it dry. If not, for $45 I can have the fellow do the stainless steel firing pin with the return spring and a new retaining pin. If I send my bolt he will do a little bit of fitting and polishing. The one symptom that still doesn't make sense is that the bolt is very hard to open after a misfire.

polymerase2 · Post by **polymerase2** » Sun Nov 27, 2011 9:18 pm

Dug out the SKS and have new clues and pictures.

To restate the symptoms:
The rifle was unissued everything is new (from the "50's)
First 100 to 120 rounds were flawless.
Began to misfire; primers were dimpled, firing pin seemed to be stuck in the rear position.
Whenever it misfired, it took two hands (after putting on the safety!!) and a very hard pull to extract the shell.
Took the bolt apart, the firing pin retainer looked "peened". Bought one online (can't remember if it was new).
Took it out and it shot 4 or 5 times then began misfiring again. (Single shots at first, then one in the chamber and one in the magazine for obvious reasons).
Same symptoms, cycles smoothly when empty, very hard to pull bolt carrier when misfires.

Pulled the new retainer and it is also "peened". Firing pin was installed correctly. Rolled it and it looked straight. Found a very small piece of metal, possibly left over from original machining. Could that be the smoking gun?????

martin08 · Post by **martin08** » Mon Nov 28, 2011 5:17 am

The electropenciled number on the top of bolt tell me that it is mismatched. Usual numbering is on the left side. The piece that was inside your bolt channel looks like it was once molten metal - which means primer material.

So, assuming the bolt is properly headspaced, there are two other likely scenarios.

1. Volcanoing of the bolt face. A small raised ring can develop just outside the outline of the primer, and cause an unsupported pressure situation between the primer and bolt face. The primers "pop" and small chunks become lodged in the pin channel.

2. Eroded firing pin hole. If the hole is too large, it can also leave an unsupported surface just outside the firing pin radius, causing burst primers.

Here is a bolt face showing the volcano ring. The previous shot had popped a primer and jammed the pin forward on the next and last shot. When the shell casing extracted, it broke the tip of the firing pin off (which became lodged in the primer). The following pic is the piece of primer that was found in the firing pin channel.

Not all is lost with your bolt, though. I would suggest sending it to Murray's Guns. He will dress the face of the bolt to eliminate volcanoing (if any), place a hardened steel insert into the firing pin hole to eliminate unsupported primers, and install a springed firing pin. His work is extremely trusted. Check the following link.

http://www.murraysguns.com/sksown.htm

desdem12 · Post by **desdem12** » Mon Nov 28, 2011 1:11 pm

Murry's guns is the best!!!! I have had mine done there and you deal directly with him and he is fairly quick also.
I HIGHLY RECOMMEND MURRAY'S ALSO.

OLD OUTLAW · Post by **OLD OUTLAW** » Mon Nov 28, 2011 1:15 pm

The last pic showing the retaining pin shouts out. That is definitely not a Yugo retaining pin.
The head is far too large to even seat into the bolt cut out for it. The rounded top on the one you show is sitting on
top of the bolt surface and not down into a flush or lower position. A non-yugo pin has to be modified slightly by
filing or grinding the head down to proper length and shape. The stem needs to be burred also to hold it in place when firing.
Just take the original pin and the new one. Compare shape and you will see the difference. A number of articles have been written on this.
The over extension of that head on the pin may well still be why the bolt does not always go into proper battery and will jam up the bolt at times.
Put the wrong pin in and because it is loose is probably what is jamming that rifle. If your bolt face is not completely closed when firing, primer
problems are inevitable. May be why you have molten metal. I would not recommend shooting it this way.

OLD OUTLAW · Post by **OLD OUTLAW** » Mon Nov 28, 2011 1:36 pm

Here is an article showing and describing what you need to do if you use a firing pin retainer that is not original
in a Yugo. Huge difference.
Couple of years ago I changed one and had similar troubles like you on the bolt not functioning properly.

http://www.sksboards.com/smf/index.php?topic=83171.0

Also, take particular note of the pics he shows with an unmodified pin in a Yugo bolt. Exact condition you have right now in your pic.
Also, notice Yugo has no weld around the pin. Chinese and Tapco do. You basically have three pins, Chinese, Yugo, and Tapco.

If the retainer is not fully seated, there will be some problems.

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