Author Topic: Sks Misfires  (Read 1225 times)

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Whitedice

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Sks Misfires
« on: March 10, 2013, 06:06:20 PM »
My older brother recently picked up a Chinese sks for me and I am having some trouble with it. I made the mistake of letting him shoot it before I got a chance to look it over. He told me it was starting to misfire after about 50 rounds and when I got it I realized it was covered in cosmoline. So I took it and cleaned it out and I also switched the stock to an adjustable stock from tapco and picked up a 20 round mag. I thought it was good to go and took it to the range but it wouldn't fire at all. I came home and looked up some information on here and found out that the reason for the misfires was probably the pin being dirty. I am new to guns in general and hadn't fully disassembled the bolt assembly to clean it just because I was worried about taking a gun apart so far. So I followed a tutorial on here and was able to get the pin nice and clean so it would move freely. I went out to shoot it again today and again had the same problem. The gun wont fire the first shot, but shoots about 50-75% of the cartridges after the first one. So cleaning the pin helped but it is still misfiring a bunch. So maybe I need a new trigger spring or something? I am definitely starting to like this gun just for the simple reason that I have never felt so comfortable with completely disassembling a gun and I have already learned alot. But I would like it if the gun would actually work as it should. So any help would be greatly appreciated.
Thanks!

BillyBang

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Re: Sks Misfires
« Reply #1 on: March 10, 2013, 07:18:57 PM »
What kind of ammo?

Do the ones that misfire show a pretty good primer hit/dent?

Have you tried to rechamber some that didn't fire the first time and try them again?

I know a lot of questions but assuming that the rifle is squeaky clean,
it could be the ammo.

Rocketvapor

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Re: Sks Misfires
« Reply #2 on: March 10, 2013, 07:23:53 PM »
How many springs does your SKS have?
Maybe one is missing  :lol:
XTREME Outdoor Store, with a Utah state license didn't realize they needed to follow separate regulations to sell scopes, bullets and rifle stocks to people in certain countries and accidentally mislabeled the packages as ATV parts

bobbers

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Re: Sks Misfires
« Reply #3 on: March 10, 2013, 07:35:18 PM »
Is it misfiring or failing to feed?  The 20 round magazine might be part of your problem.  If you'll look at the suggestions and help thread there's a sticky on how to post photos.  Some pics might help.  Short of that it's likely there are any number of things that could contribute or be the sole cause of the problem so please be patient and try one thing at a time, no matter how frustrating that might be, ok?

Whitedice

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Re: Sks Misfires
« Reply #4 on: March 10, 2013, 10:25:58 PM »
I tried using herters, and then I had a few rounds of 2 different brands that I'm not sure of. All 3 of them did the same thing. And the ones that didn't fire really didnt show any sign of being hit. I also tried to reshoot a few that misfired but didn't really keep them separate from the rest because I wasn't really thinking the ammo was the problem. So not sure if they shoot on the second try.
 And bobbers, as far as I can tell it is misfiring. I did have some trouble getting it loaded with the mag, but I tried taking it out and loading one round in at a time and still experienced the same problem. Thanks for all the sugguestions so far, I will make sure to keep the ammo separate next time to see if that's the problem. But I was curious if the hammer just isn't hitting the firing pin hard enough. Still wouldn't explain why it would work sometimes though.

bobbers

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Re: Sks Misfires
« Reply #5 on: March 10, 2013, 10:45:52 PM »
Look at the ammo, dumb as that may sound, and see what the depth of the seating is on the primers.  On occasion a batch gets made where the primers are seated a bit too deep.  And if the firing pin is worn, and that can happen, it might not be as long as necessary.  I'm assuming you reassembled the bolt exactly the right way and nothing got reversed or anything like that.  And even having cleaned it, if a primer "popped" and a wee bit of debris got stuck it can create the problem you describe.  Take out the bolt and shake it, the firing pin should 'rattle'.

Visually look at the bolt face to make sure it's perfectly flat; if it's either 'raised' or 'sunken' a bit you can have misfires as well.

I know, a lot to digest, but that's the limitations of the written word, sorry.

Whitedice

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Re: Sks Misfires
« Reply #6 on: March 11, 2013, 07:26:26 PM »
http://imgur.com/a/FWiny
There are some pictures. Sorry, they are a little blurry. Everything looks good to me but I wouldn't know if there was anything wrong because I have never really dealt with these. Maybe you guys will see something that sticks out.

How would I tell if the primer is 'popped'? I noticed a post on here about it but it didn't make much sense. And I took the bolt and shook it and it rattled up and down but there was very little side to side movement. Perhaps I should clean it again? Not sure how much cleaner it could get though.

And then for the bolt face. I don't know if it is risen or sunk in but hopefully you could tell from the pictures.

Once again, thanks so much for your help.

BillyBang

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Re: Sks Misfires
« Reply #7 on: March 11, 2013, 09:08:05 PM »
http://imgur.com/a/FWiny
There are some pictures. Sorry, they are a little blurry. Everything looks good to me but I wouldn't know if there was anything wrong because I have never really dealt with these. Maybe you guys will see something that sticks out.

How would I tell if the primer is 'popped'? I noticed a post on here about it but it didn't make much sense. And I took the bolt and shook it and it rattled up and down but there was very little side to side movement. Perhaps I should clean it again? Not sure how much cleaner it could get though.

And then for the bolt face. I don't know if it is risen or sunk in but hopefully you could tell from the pictures.

Once again, thanks so much for your help.


When you press the FP forward in the bolt.
how much protrusion is there?
It should be around 0.063" or about 1/16".

Being there is no FP mark on the primers of thd mis fired ammo,
it could mean something else is going on.
The bolt may not be the original and is giving problems on the head space.
Or there is something else not allowing the bolt to drop down as far as required.
The firing pin itself may have a problem or the inside of the bolt has some
foreign material keeping the FP from coming forward.




Whitedice

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Re: Sks Misfires
« Reply #8 on: March 11, 2013, 09:35:01 PM »
http://imgur.com/a/LhTsS

Once again, pics are a bit blurry but 1 is with firing pin all the way forward and the other is with it back. It looks to stick out about 1/16th of an inch.

You mentioned the bolt may not be able to drop down far enough. How could I tell if this was the problem? would it be a visual thing, if so, what exactly should I look for.

Toad

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Re: Sks Misfires
« Reply #9 on: March 11, 2013, 09:38:29 PM »
Seeing as it has been fired in cosmoline, have you cleaned out the gas system?
Prepping and Survival...see Survivor's sister board, http://survivorsprepboard.com/smf/

Whitedice

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Re: Sks Misfires
« Reply #10 on: March 11, 2013, 09:45:40 PM »
Seeing as it has been fired in cosmoline, have you cleaned out the gas system?
Yep. :)

Rocketvapor

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Re: Sks Misfires
« Reply #11 on: March 11, 2013, 11:06:55 PM »
There are some videos on SKS functions, I tried to make one tonight but lighting didn't cooperate.
There seems to be a communication problem with questions and answers in this thread.
Could you answer these:

With the Trigger Group removed (put safety on to remove),
cock the hammer and push down on the disconnector.
Was it free to move, and the hammer stays caught on the sear ?
Try it a few times to make sure the cocked hammer doesn't touch the disconnector.

With fingers on either side of the disconnector, line up the Trigger Bar with the Sear and drop the hammer.
Did it go WHAP !!  ?

Looking into the bottom of the rifle action, cycle the bolt and watch the bolt "drop down".
Move the bolt slightly in and out of battery and watch the bolt drop then lift.
Does the bolt drop into battery?

Shine a flashlight into the action and find the firing pin.
Take a pencil, or screwdriver and press on the back of the firing pin.
Can you move it?

With safety on, hammer cocked, put the Trigger group back into the rifle.
Turn safety to fire, pull the trigger (make sure there is no round in the chamber)
and listen for the loud Whap !! of the hammer.
Does the hammer drop each time you cycle the bolt and pull the trigger ?

Take a FIRED CASE with NO BULLET and manually chamber it, drop the bolt.
Pull the trigger.  Does the hammer go WHAP !! each and every time ?


Don't play with live rounds unless you are someplace you can safely fire the weapon.

With about 1/16 inch of firing pin travel it is unlikely that the pin will not hit the primer, even with a deep set primer. 
Something around 0.015" is deep set.  Might not be all that reliable but it will dent the primer if the bolt drops into battery and the hammer WHAPs the pin. 
Add up excessive headspace (maybe 0.008"), a deep set primer (maybe 0.015"), a volcano ridge on the bolt face (about 0.004") and you still have a dented primer.


« Last Edit: March 11, 2013, 11:23:26 PM by Rocketvapor »
XTREME Outdoor Store, with a Utah state license didn't realize they needed to follow separate regulations to sell scopes, bullets and rifle stocks to people in certain countries and accidentally mislabeled the packages as ATV parts

jbanzai

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Re: Sks Misfires
« Reply #12 on: March 11, 2013, 11:22:05 PM »
Is there cosmo in the trigger group?  Did you clean the trigger group aggressively and not oil the friction points generously after?  These may be long shots, but both have caused major FTF's in my first SKS. 
WTB Chinese SKS, numbers matching, excellent condition early /26\ with threaded barrel and milled trigger guard

BillyBang

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Re: Sks Misfires
« Reply #13 on: March 12, 2013, 06:32:04 PM »
You mentioned the bolt may not be able to drop down far enough. How could I tell if this was the problem? would it be a visual thing, if so, what exactly should I look for.

That's what we're trying to figure out and to be quite honest,
you haven't been too lavish with the information about your rifle and it's condition.

What I alluded to, in my previous post was,
whether or not you had an all matching numbers rifle, especially the bolt.
Does the bolt number match the rest of the rifle?

Does the hammer drop when you pull the trigger (even at the times that the misfires occur)?
Or does the trigger act mushy with no hammer drop?
You see, a misfire is when the hammer drops, the FP hits home and there's no ignition.
So we need to use the correct terminology when explaining the problem.
You might be having a "Failure To Fire" (FTF) which could be caused by mechanical problems.

You also weren't very clear on whether or not you gave the entire rifle
a thorough cleaning including the trigger group and bolt.
Have you?
If you haven't,
then first thing, before you try anything else, I would completely strip the rifle and give it a thorough
cleaning as laid out in these instructions.
Then if the problems still exists, we've at least eliminated the chance that there is some
foreign matter interfering with the function of the mechanics of the rifle.
Once we have that established, we can go on to other reasons for the problem.









Whitedice

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Re: Sks Misfires
« Reply #14 on: March 12, 2013, 08:32:18 PM »
BillyBang,
Sorry if I was not clear providing information. As I mentioned, Im not very familiar with these rifles yet so if I use the wrong terminology, feel free to correct me. As far as the cleaning the gun, I have completely stripped it down and cleaned it. Also, this gun is not a numbers matching rifle.

jbanzai,
There is not cosmoline in the trigger group, however, I may not have oiled the friction points well enough after cleaning. I have always tended to go light on the oil. I will oil it up a little more and see if this helps out at all. For oiling the trigger group, should I just use regular rem oil? This is what I did. But I saw some people putting some grease like or thicker oil on it if that makes any sense.

Rocketvapor,
 "cock the hammer and push down on the disconnector. Was it free to move, and the hammer stays caught on the sear ?"
     I removed the trigger assembly and the disconnecter moved when I pushed on it and the hammer remained cocked.

"With fingers on either side of the disconnector, line up the Trigger Bar with the Sear and drop the hammer.
Did it go WHAP !!  ?"
   I'm not entirely sure what you meant by this. So maybe I'm answering something you didn't ask. But with the trigger assembly back in place, I cycled the bolt back to cock the hammer and removed the receiver cover and recoil spring to watch. I pulled the trigger and the hammer did hit the firing pin with a whap.
   
Also, when I cycled the bolt it dropped into the battery. I think. With the bolt fully closed the rear of the bolt would drop about a little more than a 16th of an inch. So I think that would be it dropping into the battery.


To everyone, thanks for all of your help and suggestions. I will try oiling up the trigger group a little more, take it to the range again and see what happens. And hopefully this post made at least a little sense. I understand that I probably sound really dumb referring to all these parts and terms with 'that' so please bear with me as I learn. As far as I can tell, as I walk through all the suggestions proposed, everything works as it should. But this is an older rifle and maybe the parts are just getting worn and I will have to deal with and occasional MF or FTF whichever it is.
Thanks!