SKS Slam Fire Demo (and a fix)

0228

The SKS rifle has a free floating firing pin. What this means is that there is nothing holding back the firing pin and preventing it moving forward and making contact with the chambered round’s primer. This becomes a problem when the firing pin channel gets gummed up with dirt, jamming the firing pin in the forward position.

The original Russian SKS design did not have a free floating firing pin but this design was dropped by the Russian and overseas manufactures of the SKS, probably to save costs.

Ben Murray of Murray’s Guns has recreated the original Russian firing pin. They cost $39 or $47 installed if you send in your bolt.

This video demonstrates an SKS slam firing and shows how the Murray firing pin fixes the problem.

It will be ordering one or more in the very near future.


Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


Advertisement

  • Josh

    This really isn’t as much as a problem as people think it is.

  • http://jovianthunderbolt.blogspot.com/ j t bolt

    I can attest to their efficacy. A buddy had the slamfire problem and this replacement worked a treat.

    Now if only my Garand wouldn’t… But that’s only when I use light primered non-surplus ammo.

  • gunslinger

    I haven’t watched the full video, but don’t other guns (M1 Garand, AR-15) also have free float pins?

  • electronics

    That video demonstrated what happens when a firing pin is stuck in the forward position, not a slam fire. A slam fire occurs when the gun is hit with enough force to send the firing pin forward hard enough to activate the primer of a chambered round. This is nearly impossible to do, as the firing pin is light and a primer requires a lot of force to activate.

    A stuck firing pin is a big problem, a free floating firing pin is not. There was even a Mythbusters about slam firing an SKS and the only way they got one to do it was to set off high velocity explosives right next to a pile of SKS rifles and I believe only one went off.

  • Erich Martell

    I’ve had one of the Murray pin mods for a couple of years now, and I would not own an SKS without one. My Norinco was one of the ones that just had problems: no amount of polishing of the pin seemed to take care of the slamfire issues. Dropping in a Murray spring-loaded firing pin has completely taken care of it.

  • JustinR

    How long before the BATFE charges the owner with having an illegal machine gun?

  • http://www.msn.com Ermac

    A lot of military rifles have free floating firing pins. The slam fire issue is overblown. Don’t waste your money.

  • Mount

    Very good video. I’m just waiting for the ATF to go in and shut that company down for unlawful possession of a full auto.

  • John C.

    Seems to me that the moral of this story is: clean your guns!

  • http://jovianthunderbolt.blogspot.com/ j t bolt

    Maybe YOUR SKS never slam fires, but the one I got to shoot sure did on American Eagle ammo. Same ammo after the mod worked without a hitch for hundreds of rounds, a few weeks later. The firing pin was not dirty or stuck. It was a fun little gun, I should get one.

  • mmathers

    Isn’t it a bad idea to show off a rifle malfunctioning and burst firing on youtube while in the US?
    I know it sounds stupid but didn’t the BATFE claim some guy (I think he was a military man) with a rifle that shot doubles had “mfg a machine gun?”

  • jdun1911

    gunslinger,

    Yes both M1 and AR15 have free floating firing pin.

    In the AR15 cases, it is impossible to have Out of Battery (OOB) discharge in semi-auto mode. The bolt must be fully closed in order for the firing pin to hit the primer. It also need a certain amount of speed for the firing pin to ignite the primer because the pin is very light.

    In full/burst auto mode there is a very very very very small chance of OOB. It’s like winning the Mega Million lottery.

  • me

    Considering the current mentality at the BATFE,and some of the cases they have pursued, I would be a little hesitant about putting a video like this up on the web for all to see.

    Or is “pulling the trigger” or “not” the whole key to it here?

  • gunslinger

    after watching the video, i have more comments to make.
    1) he didn’t use the same ammo. i’m not an ammo junkie, but my science background has taught me to test only 1 thing at a time (ammo or firing pin)

    2) the rusty was keeping the pin forward, not the fact it was free floating. i bet i could “rust” a spring return pin in the forward position (such as a mosin 91/30 although it’s a bolt action and not semi-auto)

    3) how would the sks work if the firing pin was replaced but didn’t have the spring? if the bolt is so jacked up that the pin was rusted, it seems like that’s the problem (again) not the free float.

    as i said, the free float pin is used in other weapons and they don’t have those problems. i mean, our US forces uses variants of the AR-15 and aren’t showing a need for a fix like that.

  • http://thoughtsonguns.blogspot.com flowmaster

    this gunsmith willfully transferred into his posession a gun that was known to shoot in a fully automatic mode. isn’t that illegal? sort of like the guy who had an ar15 slamfire at a shooting range which resulted in him getting locked up for having a full auto, even though it was just a broken gun.

    • http://www.thefirearmblog.com Steve

      If a gun slam fires it should be sent to a gunsmith. It is a malfunction not a machine gun. Saying that the ATF have some strange ideas …

      If anyone wants to cite BATFE precedent, please go right ahead …

  • Big Daddy

    I had a chance to buy one of those SKS rifles real cheap many, many years ago. In NY state all you needed was a drivers license those days. But to have it in NYC you needed a permit which was easy to get then.

    Oh well……I’s had no legal place to shot it then. But it is a nice rifle. The guy had an old Garand and the SKS…..I which I bought both now and just kept them even if I never shot them.

    New York City really stinks about their gun laws. But with all these people here I guess them having guns easily would make things really bad. A day on the streets of Manhattan if you’re not used to a big city is enough to want to hide for a year or two. Imagine being pushed and bumped into by about 10,000 people you never saw before. That’s a day in the city….LOL.

    The gun should have used the same ammo and there were other issues about the test. It was NOT very scientific. But I am sure his firing pin setup is an improvement and if I did own an SKS I would look into upgrading it that way. It looks like a sound idea and improvement.

  • Tuulos

    Military ammo usually have harder primers than civilian ammo, so military has no trouble using free floating firing pins. When you use a civilian ammo in military weapon, the risk of slam fire increases. For example, when Sako made the 92S (civilian version of the RK-95TP) they added a return spring for the firing pin to prevent the softer civilian ammo to fire when the bolt is released forward.

    @gunslinger, S&B ammo have softer primers than the original russian ammo that was used in the first part, so he demonstrated that he could shoot softer primers without the risk of slam fire.

  • Flashman

    An over-hyped topic imo.

    If the firing pin is loose and rattles freely in the block it’s hard to understand why an SKS is “slam firing” ostensibly because of a stuck firing pin diagnosis. It’s illogical.

  • dt

    The “guy” everyone seems to be talking about is David Olofson. For details go to Gun Owners of America website and scroll to the bottom where there is a link called Olsofson update. While your there become a member. They do the work the NRA will not. They led the way on overturning the DC habdgun ban, They are helping Mr. Olofson, and are the real defenders of the 2nd admendment.

  • jdun1911

    mmathers,

    Yes the ATF put an AR15 owner to jail because his AR15 malfunction. The malfunction was a worn out trigger group that cause his AR15 to went auto at the range. Unfortunately for him there was police officers in the area when it happened.

  • Brian in CA

    Those folks claiming slamfires with the SKS aren’t an issue should be aware the original SKS 45 had a firing pin spring. The SKS therefore lacks any design feature to stop a forward positioned firing pin jammed in the bolt from making the gun run away.

    For example, the receiver bridge of the M1 Garand/M14 series has a clever slot cut into it that matches the “tail” of the firing pin, so the forward position of the bolt when closed is a pre-requisite for the firing pin being able to move forward and strike the primer.

    The Russians found the SKS very expensive to build, and tried some “economy” solutions to this problem. In the end, they transitioned quickly to the stamped sheetmetal variant of the AK-47 (the AKM) and let their client states pick up SKS production.

    This modification returns the SKS to a close facsimile of its original design, and makes a great little rifle that much safer to use.

    Regards,
    Brian in CA

  • Brian in CA

    Might as well dump that previous comment, no one cares about the Garand design in this context.

  • Cymond

    As a note to some of you who have not examined an SKS bolt and firing pin, the front of the firing pin and the front of the channel in the bolt are both conical. Driving a cone-shaped pin into a cone-shaped hole could cause the part to stick in a forward position strongly enough to activate a soft primer. It is somewhat similar to difficulties extracting a fired case from a rough/damaged chamber. My SKS has never shown any problems but I keep it squeaky clean. I can also understand a little paranoia in this post-Olofson world.

  • gunslinger

    I think there are 2 different issues here with “slam firing”
    1) A situation where the firing pin is locked in the “forward” position due to some defect (dirt, grime, rust, corrosion, out of spec). This is what was the cause of the problem in the video

    2) a situation where the forward force of the bold closing causes the firing pin to continue moving forward after the bold has come to a stop, thus causing a round to fire.

    now, both situations are technically slam fires, but they have different root causes.

    personally, i’m not saying slam fires are an not issue, i’m saying that the problem noted is not “fixed” by the solution presented. if the original owner would have cleaned their firearm prior to shooting, they would have realized the pin was in the forward position. if the parts were too rusted/corroded they should have been replaced. (not sure how that works with C&R rifles due to the laws). If the owner had a “clean” rifle and the pin was able to float freely, then i’d more inclined to believe Murry’s solution was needed.

    However I’ve seen plenty of SKS videos where there were no slam fires. I think this could have been avoided if the original owner would have taken the time to car for/clean his firearm.

  • Tuulos

    Actually, the presented solution fixes both of the problems you mentioned. If you check his website for the desing, his desing isn’t tapered like the original firing pin, preventing it from getting stuck. I also noticed that nowhere in his site he claims that the free floating is the main/only/a problem.

  • TheAmdMAN

    @jdun1911

    Haha I’ve never heard of the David Olofson case so I went looking around on the Internet. It’s funny how many versions of this are out there. Some saying the guy testified Olofson told him to switch it to position 3 to shoot auto, some say he loaded a mag and as soon as the bolt shut 3 rounds came out, some say he pulled the trigger twice each firing 3 shot bursts then it jammed.

    I am really curious to know which story is true….

    http://www.wnd.com/index.php?fa=PAGE.view&pageId=65455

    http://www.jsonline.com/news/wisconsin/29561634.html

    http://www.gunowners.com/olofson.htm

    Guess I’ll file this in the ‘unknown’ category right now…. Disappointing..

  • Paul D.

    Why did you use Sellier and Bellot ammo after the Murray’s firing Pin was installed and NOT the same ammo (Russian Berden primed) used with the original firing pin?

    Will the Murray’s firing pin not work on the harder Berden primers?

  • bill

    I know this is an old topic but just in case someone were to stumble upon it as I just did here’s my $.02.
    First, he likely wanted to show that his rifle malfunctioned even with hard primers and now he can use soft primers safely so his method is sound. I can’t say his product does nothing because it would obviously reduce risk of slam fire, but parts replacement becomes difficult with nonstandard parts.
    However I do agree with the consensus that maintenance is paramount in performance of any machine, and that this system isn’t necessary.
    Most of the people who mentioned their troubles here diagnosed their problem…. domestic brass cased boxer primed ammo. The sks has been an entry-level military pattern rifle for decades now because of price and its lack of “evil” looking features that raise eye brows and scrutiny in some more conservative traditional circles. Those with these concerns often bring the beliefs of their paradigm and don’t realize they aren’t holding grandpas deer rifle. The weapon is designed for milspec ammo not commercial brass, which can also rupture and tear. I know right now hunters are scoffing because they’ve either seen or heard about fmj or HP ammo’s lackluster performance on game, which I’m not denying. However, 125gr soft silverbear or barnaul (both from barnaul plant) are quite accurate, effective, and affordable, my deer went 25yds this yr using this from an AK. So bottom line is use steel cased ammo and leave the domestic rounds for ruger mini-30’s, It’s for them as they have weak firing pins that are known to fail with hard primer.
    Enjoy shooting cheap Russian but clean your gun. Often people get that backwards because of legends based on AK’s, which are completely different operationally. Despite myth you can’t bury the sks for a decade and expect reliability, I’ve had two require a hammer and punch to get unseized just from sitting in the safe too long. AK’s they are not.

  • bill

    I know this is an old topic but just in case someone were to stumble upon it as I just did here’s my $.02.
    First, he likely wanted to show that his rifle malfunctioned even with hard primers and now he can use soft primers safely so his method is sound. I can’t say his product does nothing because it would obviously reduce risk of slam fire, but parts replacement becomes difficult with nonstandard parts.
    However I do agree with the consensus that maintenance is paramount in performance of any machine, and that this system isn’t necessary.
    Most of the people who mentioned their troubles here diagnosed their problem…. domestic brass cased boxer primed ammo. The sks has been an entry-level military pattern rifle for decades now because of price and its lack of “evil” looking features that raise eye brows and scrutiny in some more conservative traditional circles. Those with these concerns often bring the beliefs of their paradigm and don’t realize they aren’t holding grandpas deer rifle. The weapon is designed for milspec ammo not commercial brass, which can also rupture and tear. I know right now hunters are scoffing because they’ve either seen or heard about fmj or HP ammo’s lackluster performance on game, which I’m not denying. However, 125gr softpoint silverbear or barnaul (both from barnaul plant) are quite accurate, effective, and affordable, my deer went 25yds this yr using this from an AK. The 154gr I’ve not used as profile is different and feeding reliability in some guns is questionable so I don’t risk it. So bottom line is use steel cased ammo and leave the domestic rounds for ruger mini-30’s, It’s for them as they have weak firing pins that are known to fail with hard primer.
    Enjoy shooting cheap Russian but clean your gun. Often people get that backwards because of legends based on AK’s, which are completely different operationally. Despite myth you can’t bury the sks for a decade and expect reliability, I’ve had two require a hammer and punch to get unseized just from sitting in the safe too long. AK’s they are not.