AR15: Slamfire

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  • turnerdye1

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    Dec 26, 2010
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    North Central IN
    Has anybody ever had this happen?

    I was at the range comparing some of my reloads to some Profire Arms stuff. The round that actually slam fired was the Profire stuff.

    What would make this happen? My gun was just cleaned the day before the range trip and it happend probably 50 rounds into the session.

    I put in a new mag and hit the ping pong pattle and the gun fired. It was quite shocking thats for sure! Luckily the gun was down range


    On a good note...my reloads shot 2" at 150 yards with some pulled M855 bullets.
     

    MtnBiker6510

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    Feb 19, 2011
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    Wow :n00b:, good thing you were observing safety rules. My 1st thought would be to check hammer/sear engagement? Maybe another, more versed person could chime in with suggestions for this malfunction.
     

    turnerdye1

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    Dec 26, 2010
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    What type of AR do you have?

    I have never had this happen.

    Ive never had this happen out of the 1300 rounds ive fired either! Its a Delton upper and lower factory built

    Yea thats not good. ive never had this happen either. I would not be using anymore of it till I got it figured out though.

    Maybe a soft primer? Because isnt the AR firing pin free floating?

    Wow :n00b:, good thing you were observing safety rules. My 1st thought would be to check hammer/sear engagement? Maybe another, more versed person could chime in with suggestions for this malfunction.

    Im glad i was following the rules as well!! Ive never taken my trigger apart before so Its nothing ive done i dont think. What exactly would i be looking for?



    And after that happened I went ahead and shot the rest of the mag and put a new mag into the well. Hit the ping pong pattle and it didnt happen again, i repeated that process on 3 mags after that as well with no issues
     

    dom1104

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    Mar 23, 2010
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    I have no idea what would cause this if it isnt some sort of jammed firing pin, other than maybe a high primer?
     

    armedindy

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    it might have been a primer issue...see if you can recreate it again..if so, then send the gun back
     

    j706

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    Dec 4, 2008
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    Free floating firing pin guns always have the possibility of slam fires. I had one on a 11'5" M16 once. The gun was somewhat temperamental with the barrel/gas setup. I had a FA misfire,cleared it and the round failed to extract (I failed to notice). When I ran the charging handle it fired but only once. But while I didn't care for that happening, the gun was pointed down range as it should have been. I always assume any floating pin gun is going to fire when I chamber a round and act accordingly.
     

    churchmouse

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    Dec 7, 2011
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    I would get into the bolt group, pull the pin out and inspect it for damage, dirt, etc. I would not have reloaded the gun until that was done unless I was being fired at. That is usually not going to happen at the range. You were very responsible to have it pointed down range but to go at it again without at least looking into the bolt group and pin is a bit scary at least to me.....JMHO
    Check that area out. It is very simple to access and inspect.
     

    sloughfoot

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    Apr 17, 2008
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    Slam fires happen. High primers in a reloaded cartridge are the usual culprit. Check all of your reloads for high primers on a flat surface. This is why I hand prime all of my rifle ammo. I check each one before they get powder and bullet. Every now and again, I get one that needs a little extra squeeze.

    I had a true slam fire with a mini-14 a long time ago. It blew off the handguard, broke the wood stock, and blew out the contents of the magazine. My ears were ringing for a week from the explosion. I sent the rifle back to Ruger and they replaced it at no charge even though we all knew it was my fault. I never did find that handguard.....

    There is no real reason to send your rifle back if the bolt lugs, upper, and the mag are undamaged. Technically you had a premature fire because the locking lugs must have been engaged so no pressure was released into the action.

    Check all your reloads.:twocents:
     

    Hillbillyblood

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    Feb 11, 2012
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    LaPorte Indiana
    I have to agree with Sloughfoot, when my AR doubled the research from numerous websites and forums spoke of high primers. When I get into reloading this will be in the back of my head. Good Luck
     

    deo62

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    seen this happen several times in the army in the early 80 s, never occured when the weapon was on safe though, generally was told it was due to inertia. By the way, my artillery unit was chock full of genius. (dont know how to make last part purple)
     

    Litlratt

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    May 17, 2009
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    As above, most likely a high primer. If it was, the spent primer will have a nipple rather than a dimple. Without pressure from the hammer on the firing pin, the primer cup material will flow into the firing pin hole in the bolt face. If it was hammer follow, the spent primer will appear normal.
     

    SERVED_USMC

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    Nov 29, 2008
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    Im going to jump on the "high primer" wagon on this one. ALL of my AR's leave a dented primer on the last round that was chambered and not fired. DO NOT DO THIS IN YOUR HOUSE, but next time you are in a safe area. Lock bolt to rear, insert mag, hit mag release, extract chambered round, observe primer. There will probably be a dent in it. If the primer wasnt completely seated it isnt unreasonable to think that thats what caused it. Good on you for keeping the muzzle in a safe direction.
     
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    Dec 14, 2011
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    Personally, I would put my money on either someone using a pistol primer and/or the primer not being seated deep enough in the primer pocket. I believe I read that the primer needs to be seated about three thousands below the base of the case. Also, pistol primers are softer. Another possibility could be excessive dirt or sand on the face of the bolt when it came forward (unlikely though). This is the exact scenario why we always keep the muzzle pointed down range!!
     

    Wild Deuce

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    Dec 2, 2009
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    Did you retrieve your brass after the malfunction? Checking the primer from the culprit casing will give you some clues. Flowback into the firing pin hole will show you that the hammer was not resting against the firing pin (therefore, no hammer follow through and no problem with the sear engagement ... a true slamfire). If you are certain that you have retrieved the correct casing and there is no flowback into the firing pin hole, you might have hammer follow through.

    Here are some pics from two slamfires I had (posted from another forum). The two casings on top are the slamfires (note the flow into the firing pin hole). The two casings in the middle are rounds that fired normally. The two on the bottom are unfired rounds from the same lot.

    attachment.php


    This is another view of the two slamfire casings compared to two fired rounds (functioned normally) from the same box (note the primers are NOT high).

    attachment.php


    It is possible to have an out-of-battery slamfire in an AR but unlikely that it would be caused by the firing pin ... more likely that the boltface or something else will strike the primer. A slamfire in an AR will more than likely take place once the bolt is in battery and the free floated pin strikes the primer due to inertia. This usually requires a high and/or sensitive primer for detonation.

    If you want to read more about my slamfire issue and all the associated wisdom that was shared with me on that forum, click here (my story starts with post 29).

    BTW, you do know that every single round that gets chambered during the firing cycle gets a little dimple on the primer? I was told that if you chamber the same round several times without firing, eventually the firing pin kissing that primer all those times might convince the primer that they are on a date and ... BANG! Also, did you chamber the round from the magazine (sounds like this is what you did from the OP) or manually place the round in the chamber and release the bolt? Just want to be clear.
     
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