I own a 1978-production O-series Yugoslavian SKS, which I use both for hunting and as my MBR.
It is a rearsenaled example with a few non-matching #'s but otherwise it is entirely original. The bolt was taken apart and the FP channel cleaned completely, and I did a light polish job to the FP itself with Flitz and a Dremel. I can report that there is no spring on the FP, as it is OEM also.
I have heard many comments about potential problems arising from the use of American ammo loaded with soft, non-MilSpec primers in these rifles, so I endeavored to test my rifle for the possibility of slam-firing.
This became a personal issue after a thwarted home invasion -wherein the sound of my SKS's action chambering a round seems to have been plenty of incentive to run the little punks off- ensued recently.
The chambered round, upon extraction, had a very deep dent in the center of the primer, and I was quite concerned about how close I may have come to giving the would-be thieves an inadvertant warning shot while also ventilating my roof!
So, this is what I did...
I loaded up several x39 rounds with all of the various primers I had laying around that would fit and proceeded to chamber and rechamber them (at the range, all safety protocols adhered to) until either they burst from the repeated FP impact or until I got tired of the exercise.
I got tired first, I am happy to report.
I had standard CCI 200 rifle primers, CCI 250 magnum primers, Winchester LRM and Remington LR primers available for this test.
None of the primers detonated after 20 full-retraction releases of the bolt carrier. They all dented deeply on the first strike but subsequent slammings did nothing apparent to deepen the strike craters.
I also had several rounds of factory UMC FMJ ammo with their small, gold-colored primers--these were affected even less than the LR primers were, as their dents were more shallow.
Just for S&G I loaded and extracted one of my handloads over 50 times (loaded with H4895 and a CCI 250 primer), and it refused to fire until I squeezed the trigger. I did the same with a round loaded with a CCI 200 primer--same thing, though I gave up and rang the 400M gong with it after my finger got sore from crankin' the bolt back several dozen times.
It would appear that most slamfires are the result of poor maintenance, as the most likely cause would be that which prevents the FP from bouncing off the primer lightly enough--something like a bit of debris in the FP channel, dried Cosmo, or a bent FP. And a bent SKS FP seems like it would be rare, as well as easily remedied.
Maybe my rifle is an exception, but I doubt it.
If in doubt about the primers in your loadings, take your new ammo and your SKS to the range and do as I did with one or two of them--if it's gonna slamfire it ought to do it within 5 or 10 loadings, I would think. Fifty repititions seemed like overkill, and that is exactly why I did it.
But now I know I don't have anything to worry about on that front, and that made it worthwhile to me.
Yep. Pretty much.
Like most military rifles, the SKS has a free-floating firing pin.
This is what causes the slight dimple.
www.murraysguns.com/sksown.htm this firing pin is sweet it goes back to the first gen sks with a spring pin it is nearly impossible to slam fire
tag to read when I get home.
Chamber a round in any AR15/M16 and you will get a slight primer dimple.
As noted, the only slam-fire SKSs I have heard of had the firing pin frozen forward by dried cosmoline.
This type of thing is not so uncommon, however with some types of .223 AK. I suppose it could happen with 7.62 AKs, but I haven't heard of any.
I have a Pre '89 Norinco 84-s, which started slamfiring one time. I would drop the bolt on a loaded mag, and the gun would go 'bang'. It turns out little primer shavings would get caught in the firing pin channel and the pin would stick forward, setting off the primer when the bolt dropped.
I now check the firing pin channel when I shoot that gun, and mostly shoot Wolff. The primers are hard enough that they don't leave shavings behind.
I had a slam fire once on a new to me and verrrry dirty chinese sks. It was with commercial ammo and all I had was a double fire with a few extra rounds in the mag that worked normally. No dried cosmo...just lotsa crud in general. Lesson learned.
I think that your care in cleaning and polishing of the firing pin has done a lot to prevent any inadvertant slam fires.
I even saw dimpling of the primer with my Remmington 870 pump gun when the head space was bad due to a bad Ithaca barrel. I was amazed that the shel failed to fire. I don't think I was as amazed as the 10 point buck in my scope was RELIEVED!!!
I think there were different firing pins through the dif. countries and years. Bought an exellent SKS book years ago, said when buying bolt/pin from different sources, some could be put together wrong, pin would be sticking out of bolt.
Put your pin in correctly and verify it is not protruding... Ideal military design would preclude being able to install parts incorrectly.
If any interest, I will get book out and quote more specifically. I think it was discovered and changed in later SKS's
BTW, I use CCI BR2 primers for my 7.62x39 handloads.
...and use Rem primers in my revolvers for the exact reason I don't use em in my semi-rifles, they are more sensitive
Excellent test, thanks for the info
I think you hit the nail on the head though with the crudded up firing pin channel. I've met a few guys at the range with their new Yugos who thought spraying a little cleaner in through the FP hole did the job. One guy refused to believe me when I told him that the FP retaining pin did in fact come out and allow a better cleaning. His rifle was doubling on Wolf because it was "a cheap piece of commie crap".
I have had 1 slamfire out of about 5 K rounds through my Chinese Type 56. I stopped shooting it, and disassembled it when I got home. The firing pin was not stuck, but I cleaned and lubed it anyway. No further occurances. I was shooting Wolf. Must have been a high primer, or an unusually sensative one.