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Thread: AR10 slam fire

  1. #1
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    lar45's Avatar
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    AR10 slam fire

    I had a friend over today shooting his AR10 in .308 and it had a slam fire with factory FC ammo. I don't know what bullet, but it was a fmj. After the slam fire we pulled the next round out of the chamber and it had a small dimple on the primer.
    What do you do to fix that situation? Is there a lighter firing pin, or???
    Any help would be appreciated.
    Thanks

  2. #2
    Boolit Master

    rancher1913's Avatar
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    probably just need to clean the BCG real good, make sure the firing pin moves back and forth and is not "stuck" in the forward position.
    if you are ever being chased by a taxidermist, don't play dead

  3. #3
    Boolit Master Moleman-'s Avatar
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    The dimple is normal with a floating firing pin. It will be worse if you put a cartridge in the chamber and let the bolt slam shut. I'd check the ammo over really well to make sure there were no high primers, clean out the firing pin recess and check your FCG for anything out of normal. They do make a lighter weight titanium firing pin which won't leave as much of a dimple on a chambered round.

  4. #4
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    Federal primers are the most sensitive but they should still be fine. Sometimes people confuse doubles with slam fries. Only feeding from the mag. also helps.
    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

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    Thanks for the info, I'll pass it along.

  6. #6
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    Texas by God's Avatar
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    Always feed from the mag only. I dropped the bolt on a breech loaded 6.8 spc and it plowed a good furrow a few feet away. I'm convinced.

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  7. #7
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    my guess is like rancher said is probably some crud in the bolt. If its not and you have it happen again one thing you can try is going with a lighter buffer spring. Personaly I don't think fed rifle primers are that much if any softer then any others. As a matter of fact I think ww are softer then feds. I have a 300 bo that wont run fed small rifle match primers a 100 percent with a reduced hammer spring but will run ww's all day long.
    Quote Originally Posted by lar45 View Post
    I had a friend over today shooting his AR10 in .308 and it had a slam fire with factory FC ammo. I don't know what bullet, but it was a fmj. After the slam fire we pulled the next round out of the chamber and it had a small dimple on the primer.
    What do you do to fix that situation? Is there a lighter firing pin, or???
    Any help would be appreciated.
    Thanks

  8. #8
    Boolit Grand Master popper's Avatar
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    Dirty/damaged FP, bad H.S. on the ammo, dirty chamber will do it. Just dropping the bolt or when cycling? Sure gets you attention!
    Whatever!

  9. #9
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    When did it actually happen? When closing the bolt or while shooting? If it happened when shooting it was a bump fire. Common with the AR platform. Usually when you are pulling the trigger real slow.

  10. #10
    Boolit Master
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    CCI #34 military primers are specifically made harder for weapons with floating firing pins to prevent slamfires.
    They will work in any rifle including bolt action where they are not needed.
    All the State cops that i know use the CCI military primers to reload their forty calibers too be cause its a hi-pressure round and apparently floating firing pins.
    If you see a dent in the primer just from chambering a round, you need the military primers too.
    My 45 auto has a spring on the firing pin to retard it from hitting the primer when chambering and then only if the hammer strikes the firing pin.
    When replacing the recoil spring on a Colt 45 auto, you need to also replace the firing pin spring as well.
    Help prevent slamfires, use military primers on floating firing pin weapons .
    The cops also shoot AR 15s. ,but they don't reload for those.I get their brass. They said if they did reload those 5.56 they would use military primers as well.
    I have a .223/20 Ga. over and under so i don't need military primers.
    Just my 2cts

  11. #11
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    It happened while shooting.

  12. #12
    Boolit Grand Master popper's Avatar
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    Bump fire. Clean the trigger parts real good (disconnector) and watch trigger control - like a double in SA pistol (limp wrist, etc).
    Whatever!

  13. #13
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    M-Tecs's Avatar
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    Quote Originally Posted by lar45 View Post
    It happened while shooting.
    That is not a slam fire. It's doubling. That can be a shooter issue and or a trigger issue.
    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

    "Before you argue with someone, ask yourself, is that person even mentally mature enough to grasp the concept of different perspectives? Because if not, there’s absolutely no point."
    – Amber Veal

    "The Highest form of ignorance is when your reject something you don't know anything about".
    - Wayne Dyer

  14. #14
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    Yep you bump fired it. Usually happens when you are really trying to pull the trigger slow. Very common on the AR platform

  15. #15
    Boolit Master Moleman-'s Avatar
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    Check your disconnector spring to make sure the big end is on the bottom, and that the hook is sharp and has good contact with the hammer. First pic is FCG with the trigger forward, and 2nd is with the trigger back as if pulled with the disconnector holding the hammer back. If there isn't enough contact, the spring is weak/installed upside down, or disconnector hook is rounded off the hammer can follow the bolt and it can cause another round to fire. If there isn't enough disconnector contact you can try a new disconnector or grind a tiny bit off of the fitment pad (pic #3 red arrow). Take off too much and the disconnector will not release the hammer.
    Attached Thumbnails Attached Thumbnails fcg1.jpg   fcg2.jpg   AR100.jpg  

  16. #16
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    Petander's Avatar
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    Yeah,bump.

    I used to have a Tromix 458 Socom with a nice Geissle trigger. Very short travel. Shooting groups from bags was hard because of too easy bump fire.

  17. #17
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    don't know how many thousand rounds ive shot out of ars but im sure its WELL over a 100 and ive done it with factory triggers worked triggers and drop in triggers and ive shot them fast and spent hours at the range squeezing for accuracy and ive never had a bump fire other then when I was intentionally trying or like Moleman showed a disconnector problem a firing pin problem or a high primer. It is not a normal occurrence on a properly operating gun. you have a lot more sensitive finger then me if you can make a gun bump fire just pulling the trigger without hooking a belt loop using a string ect. Especially the typical 6-9lb trigger pulls milspec kits come with.

  18. #18
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    AR10 slam fire

    I have unintentionally doubled before with an AR.
    Much more likely shooting from a bench and with a light trigger.
    I don’t think I have ever done it standing.



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  19. #19
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    BigAlofPa.'s Avatar
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    Now and then i'll double fire with my 1911's. It can be surprising.
    One round at a time.
    Member of the NRA,GOA and FAOC. Gun clubs Zerby rod and gun club. Keystone Fish and Game Association.

  20. #20
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    id bet at least 90 percent of the rare occurrences of doubles with ars can be traced to someone who has gave himself the title of gun smith. PLEASE at least leave the disconnector alone and that includes the reduced spring for them that comes in a spring kit.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
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GC Gas Check