Slamfiring?

Discussion in 'Gunsmithing Forum' started by drake85, Apr 12, 2010.

  1. drake85

    drake85 New Member

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    I am currently going through a gunsmith school online and had a question about good ways to prevent slamfiring. Any advice is appreciated
     
  2. Dillinger

    Dillinger New Member

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    On a boltgun? Generally your trigger has been adjusted to be too sensitive ( light in pressure ) and the resulting closing of the bolt handle against the action causes it to go off.

    Easy fix, add some more weight to the trigger so the trigger pull is "heavier".

    JD
     

  3. NGIB

    NGIB New Member

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    The only slamfire I have seen with a semi-auto handgun was caused by junk in the firing pin channel which prevented the pin from fully retracting - scary when it happens...
     
  4. amoroque

    amoroque New Member

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    Dumb question, but what is slamfiring? Never heard that term before. :confused:
     
  5. NGIB

    NGIB New Member

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    Basically, the round goes off as soon as the action closes - without touching the trigger...
     
  6. amoroque

    amoroque New Member

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    Thanks NGIB! I appreciate the info!
     
  7. ThorsHammer

    ThorsHammer New Member

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    I've heard of slam firing but do not quite understand the mechanics behind the process. Let's say I have a semi-auto with 17 rounds in the magazine. Would it be possible for the semi-auto to slam fire through the whole magazine or does it inherently fail somewhere along the way? I mean, I'd probably limp wrist it after the first two, so maybe I'd get a stove pipe and that would be the end of it. :eek:
     
  8. mrm14

    mrm14 Active Member

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    Garrand type actions such as the M1 Garrand and the M-14/M1A have floating fireing pins. Usually one gets into trouble with slamfire when reloading for these actions. Primer has to be flush or a tad lower in head of cartridge and case trim height is somewhat critical as well, or slamfire could occur. In these actions, when slamfire occurs the round can go off before bolt totally closes. VERY, VERY, VERY BAD JU JU if this occurs in these actions.
     
    Last edited: Apr 12, 2010
  9. NGIB

    NGIB New Member

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    If the problem that caused the slamfire doesn't fix itself and there isn't a feeding malfunction, you'll rip off the entire mag in full-auto. When it happened at the range I was shooting on, the fella only had 3 rounds left in the mag so it was over real quick. Don't remember exactly what kind of pistol it was but I do remember seeing the firing pin protruding from the breech face with the slide open...
     
  10. stalkingbear

    stalkingbear Well-Known Member

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    It's impossible to say what steps are necessary to prevent slamfiring without 1st stating the type/make/model of firearm it is that's slamfiring. That's because the problem would be different for example a semiauto pistol and a semiauto rifle or even bolt action rifle.
     
  11. Ruzai

    Ruzai New Member

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    I've heard this also happens when you dont seat the primer deep enough into the head of the casing and the action closes and crushes the primer, making the gun fire. Scary to think you could rip a whole mag with slam-fires if your firing pin gets stuck forward. I'm sure the pressure on the chamber and battery are hellatious since most of the time the chamber isnt completely closed.
     
  12. c3shooter

    c3shooter Administrator Staff Member

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    Agree with da Bear. Winchester Mdl 100s have slamfired as result of broken firing pins- hence the recall on Model 100s for a fp retrofit. A semi, bolt, lever or pump with a badly worn sear or sear notch may release the striker/hammer due to shock of action closing smartly- cure is replace worn (or more likely, Bubba'ed with a Dremel) parts. SKS- no spring on firing pin- dried cosmoline in FP channel of bolt causes FP to stick in forward position. Cure is to clean the 50 years of dried gunk out of the bolt (was involved in a lawsuit over that very thing) 1911A1 with bad disconnector- sometimes would double- usually hammer would just ride slide forward. Replace disconnector. Different arms will have different causes, different cures. Will gun FTF before running out of ammo? Maybe. If yer lucky.
     
  13. ThorsHammer

    ThorsHammer New Member

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    That's insane. I hope I never see one of those on the range, and if I do, I hope the person has enough sense to keep the weapon aimed downrange for as long as humanly possible.
     
  14. Fisherking

    Fisherking New Member

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    I had a friend have this happen on his sks with ten rounds and I have had this happen on my sks like a double tap. I changed primers to harder ones and the problem went away. I tryed to get the fireing pin spring set up for the sks but with the new Oboma admin charging huge export fees and a ton of paper work I was unsecsessful to be able to get on into Canada.:(
     
  15. superc

    superc Member

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    I had a Jennings J-22 slam fire on me once. Very unnerving. I had been to the range that day, fired a bunch of weapons, the little Jennings amongst them. They were all placed empty into a haliburton case then brought home. I then cleaned most of them but hadn't gotten to the Jennings yet when I realized a nearby grocery would soon be closing and I needed to buy some milk before it did. My 38 was still dis-assembled for cleaning so I just grabbed a loaded magazine and loaded the Jennings. [In those long-ago days I used a wallet holster in my back pocket.] As I always had I racked the slide to chamber a round (with my finger nowhere near the trigger) when the gun suddenly fired. Some fuss ensued. Later exam of the fired .22 casing (still in the gun) revealed a strange dent in the case rim and a bulge of the case. Exam of the gun disclosed that sometime during the day's firing a shaving of brass had somehow wedged the extractor in the down (inward) position.

    As most here know the extractor is supposed to just slide over the rim of the cartridge case, then hook it upon a firing and pull the case out of the chamber. In this instance instead there was no give to the extractor and it became a firing pin when it slammed against the rimfire cartridge rim. A total UD experience. No one hurt, but it got my attention. That was the end of my routine use of the Jennings and rimfire as a back up piece and a 'new' WW2 era PPK using centerfire cartridges replaced it within a week.

    With hindsight, either one of two simple rules not followed could have prevented that slamfire. 1) Clean any gun that has been fired before loading it. 2) Inspect your weapon before loading it, even if it was just fine earlier that day.
     
    Last edited: Apr 17, 2010
  16. drake85

    drake85 New Member

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    Thanks a lot for the input guys it's much appreciated and a lot of help.
     
  17. k2enemy

    k2enemy New Member

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    Here is my take on slam fires and out of battery firing.
    1. The firing pin protrudes its channel or has too small of a tolerance between the striking point of the pin and the primer
    2. Firing pin is somehow stuck from foreign objects in the pin housing or gunk has built up in it
    3. The weapon has a floating pin, meaning it does not have a spring around the pin to keep the pin retained until it is struck by the hammer and improper ammo is used like commercial 30-06 in an M1 Garand. Often these primers are too soft to withsatnd the force of the floating pin and will fire without being in full battery or fire when in battery.