Pennsylvania Firearm Owners Association
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  1. #1
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    Default AR15 rear pivot pin screw

    Does anyone know what size they are and what they are called (technically) I'd like to order a bunch.
    Thanks.
    FJB

  2. #2
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    Default Re: AR15 rear pivot pin screw

    The rear takedown pin is retained by a detent pin and a spring that are held into the receiver by the receiver end plate. There is no screw.


  3. #3
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    Default Re: AR15 rear pivot pin screw

    Are you speaking about a 4-40 set screw that some lower receivers utilize


  4. #4
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    Default Re: AR15 rear pivot pin screw

    Huh! Learn something new every day.

  5. #5
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by imashooter2 View Post
    Huh! Learn something new every day.
    Some lowers also use 4-40 set screws on bolt catch pin 🤗

  6. #6
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by GOYABEAN View Post
    Are you speaking about a 4-40 set screw that some lower receivers utilize

    THIS^^^^ I tap mine and have been using screws from my rc planes and cars but I'm all out of them.
    4-40 set screw.. Never knew the size.. THANKS!
    FJB

  7. #7
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by bogey1 View Post
    THIS^^^^ I tap mine and have been using screws from my rc planes and cars but I'm all out of them.
    4-40 set screw.. Never knew the size.. THANKS!
    Your very Welcome 🤗

  8. #8
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by bogey1 View Post
    THIS^^^^ I tap mine and have been using screws from my rc planes and cars but I'm all out of them.
    4-40 set screw.. Never knew the size.. THANKS!
    You can get a bag of 100 from Amazon for cheap. Mine came with the allen wrench. They don't need to be real high grade because there is no load to speak of.

    Do get a decent tap (and wrench) to cut the threads. You don't *need* to drill out the hole if you've got a good tap and go slow.

  9. #9
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by GOYABEAN View Post
    Some lowers also use 4-40 set screws on bolt catch pin ��
    It*s not a 4-40 set screw for the bolt catch. It*s a 308 bolt catch pin. These are called the *Enhanced* lower features. A 4-40 set screw for the Pivot pin detent & spring, threaded for the 308 Bolt Catch pin, (as I outlined) & a nylon tipped 1/4-28 set screw behind the grip screw that takes the play out of the upper & lower. Eliminate the well known *Rattle* between Upper/Lower. I*m actually switching to a new brand of 80% 7075-T6 Billet Lowers for the AR*s I build & these new ones have the enhanced features.

    BTW: anyone can do these *enhancements* on their own.



  10. #10
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    Default Re: AR15 rear pivot pin screw

    Quote Originally Posted by Sgt.K View Post
    You can get a bag of 100 from Amazon for cheap. Mine came with the allen wrench. They don't need to be real high grade because there is no load to speak of.

    Do get a decent tap (and wrench) to cut the threads. You don't *need* to drill out the hole if you've got a good tap and go slow.
    100 because 99 of them will be all over the basement I ordered 10 for 3 bucks shipped.
    That'll do me foe a while. I have a harbor freight tap that works pretty good, yep no drilling,
    dont know why I said that.
    FJB

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