DIY AR-15 Build: Pivot Pin Installation - ITS Tactical

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DIY AR-15 Build: Pivot Pin Installation

By The ITS Crew

4 of 8 in the series DIY AR-15 Build

Today in part four of our DIY AR-15 Build you’ll learn how to install the Pivot Pin on your Lower Receiver and hopefully take our recommendations on board for a happier stress-free build!

This can either be one of the most complicated steps in assembling a lower receiver, or a relatively easy one. It just depends on your tool selection.

When inserting the detent that holds in the Pivot Pin, it’s quite common for it to turn into a Pegasus Missile and shoot across the room along with the spring that’s under tension. In this article we’ll describe a good method to utilize and mention a tool that will help avoid detent missiles!

Pivot Pin Installation

One of the reasons we like the Stag Arms Lower Parts Kit is that it comes with one extra detent in case yours takes off into the atmosphere during this assembly. As mentioned this step can be fairly simple depending on tool selection. You can get away with what we use in the video below, which is needle nose pliers, a hex wrench and a small punch.

If you want to avoid frustration, we highly recommend the Brownells Pivot Pin Installation Tool, which is a cylinder that fits into the Pivot Pin ears and has a small cutout for the detent. You simply insert the spring, slide in the tool, put the detent into hole and push a small punch in and turn. This traps the pin without the Pegasus Missile effect. This will of course make more sense when we describe the installation in detail below.

DIY AR-15 Build: Pivot Pin Installation

Parts Needed:

DIY AR-15 Build: Pivot Pin Installation

Tools Needed:

Assembly Instructions

DIY AR-15 Build: Pivot Pin Installation

  • Put the lower on the vise block and tilt it towards you to so you can work easier.
  • WARNING: The Pivot Pin Spring and Detent can launch out during this section and if you lose them you’d better have good eyes or you’ll be ordering replacements!
  • Insert the 3/16 Hex Wrench from the port side flush with the outer starboard side pivot pin ear.
  • Insert the Detent Spring into the Detent Spring channel in the lower.
  • Using the needle nose pliers, grasp the detent and push it onto the spring. Once it inserts into the channel, take a small punch and hold it there.
  • Carefully slide the punch away as you maneuver the Hex Key over the spring and detent, capturing them.
  • With the flat cut section of the Pivot Pin facing aft, slide it over as you back the hex key out.
  • You’ll now be able to test the Pivot Pin’s functionality by ensuring it’s capturing the detent as it moves back and forth.

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Join us back here soon for our 5th installment in the DIY AR-15 Build where we’ll be assembling the Trigger Group!

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  • Fastlane

    The longest part of my build was finding the detent post-launch. It had bounced off three walls clear into the next room.

  • Josh C.

    I use a utility knife blade to hold the spring and detent pin in place while slipping the takedown pin over and into place. This works great if you don’t have the install tool, or for some reason have to make the repair in the field. Thanks for the articles!

    Josh C
    Chattanooga, TN

    • Good tip Josh!

    • Tom F.

      After several failed attempts using a punch to capture the detent, I used a 1/16″ X 1/4″ Popsicle stick to hold the detent while I sipped the pivot pin in. That worked great the first time! This is similar to the utility blade concept described earlier.

      Thanks for all the great ideas!

  • JM

    The Brownells Pivot Pin Install Tool is definitely a must have, but I still had a couple of detent/spring missles fly across my room before finally getting the pivot pin installed. Thanks for doing this series b/c the more people who know how to build a LBR the better.

    • Couldn’t agree more JM! Thanks for the kind words and support!

  • Pudge

    An 1/4″ adjustable clevis pin works great. Any hardware store should have them and they are around a buck.

    • Pudge, interesting on the Clevis Pin. Never even heard of one of those before you brought it up. Might work perfectly if the hole in it is large enough for the spring and detent.

    • Pudge

      The holes on a 1/4″, fit the detent perfect. Used on my first build and got takedown pin first try and it was truly simple.

  • Alex Yuam

    All I do is put in the spring and the detent in and push it all the way in and put a thin, but sturdy card like a business card and then I push the pivot pin in and pull the card out.

  • AJ

    A handy tip for any build using small springs and pins is to do the work inside of a gallon ziplock bag. That way, when the part launches from your hands, it only travels a coupe of inches before landing inside the bag. Another tip for building ARs (or any guns really) is to put a wrap of electrical tape on the jaws/tip of any tool you use (like pliers/leatherman) so you don’t scratch the finish if you slip.

  • Valuable info. Fortunate me I found your site by chance, and I am surprised why this twist of fate didn’t took place earlier! I bookmarked it.

  • Allen

    redo the video! lol. spring pops out, cand find it, no one on camera. aannnnddd CUT!

  • Alan

    So I just completed my first build and it went so smooth, thank you for these videos they came in incredibly handy…. However I think i have found a cure to your detent installation issues. I found holding it in with a thin butter knife did everything i needed it to do, no need for the hex wrench or the multi tool, just man hand the detent in, hold it flush with the butter knife and the takedown pin slides right in no problem….

  • Great video series. I just order my stripped lower, a stock and the kit and am excited to begin my very first build. I purchased a killer upper at the gun show a couple of weeks ago and am now ready to get this thing rockin. Thanks for taking the time to make these valuable videos. Airborne!

  • Tim Curren

    I found the videos to be extremely useful, although I struggled with the front detent pin for quite awhile chasing it around the room before finally getting it installed. This was my first build. I recently built a lower for a friend and used a standard razor blade and needle nose pliers to install it on his. Buy using the pliers toget the pin started and the razor blade to hold it in place the take down pin slides right by the razor blade for quick and painless install. Thanks again for the videos.

  • Brian C.

    Great vid. Used the Brownells tool and completed this task in less than 30 seconds. Pushing a punch through the hole in the tool completely alleviates the concern of the detent flying out. Push in, rotate and the detent is trapped. Slide in the pivot pin and you’re done.

  • Matt

    Why not just use a punch to compress the spring, slide a paperclip in the small hole in the side to hold the spring compressed, drop the detent in, slide the pin through, then remove the paperclip? Is that not possible for some reason?

  • Matt C

    Hi.  This is really easy.  I inserted the spring.  Then, I got a small pair of tweezers and held the detent from the side above. Carefully push the pivot pin down until it fits through the hole and insert.  …done.

  • WxMan_II

    I’m kinda wondering….  looks like this could be done fairly easily using a relatively stiff feeler gage.  I’ve got a set left over from the old points and condenser days that I haven’t used in ages..

  • NinaDecker

    I managed to get the installation done pretty easily, thanks to this video. But once installed, the pivot pin didn’t move in and out as well as yours did in the video. Not sure if this is okay?

    • NinaDecker Hi Nina, they can be stubborn depending on the tolerance of the pin or the hole. Use a little Slip2000 or other lubricant to help if it’s an issue. Over time it may loosen up on its own too. Hope that helps!

    • NinaDecker

      Thank you Bryan! Your videos are making this happen! 🙂

  • JoshJaeger

    using a razor blade to dolt the detent back works better- then just slide the pivot pin in while holding the detent with the razor blade- much easier!

  • gtollers

    Install spring into a magnet on back side of pivot pin with detent will stay in place. Place detent in receiver and slide pin into place. You will lose zero parts shooting across room.

  • Taylor

    Pivot pin is stuck and won’t move. I didn’t everything as instructed in the video and other videos. Any ideas? I am concerned it’s ruined. Thanks!

  • Taylor

    Pivot pin is stuck and won’t move. I did everything as instructed in the video and other videos. Any ideas? I am concerned it’s ruined. Thank [email protected]

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