I recently put an upgraded barrel into my factory AR15: it was shooting fine, but recent experience putting together a 6mm ARC from an Odin Works upper raised my expectations of gas gun accuracy.

Anyway, after installing the new barrel I noticed some play between the upper and lower receivers. I’m sure it had always been there, but I decided to try some oversized takedown pins from JP Enterprises to help reduce the wiggle.

The takedown pins in these rifles are held in place by spring-loaded retaining pins. There are excellent internet videos on how to get takedown pins out and how to get them safely back into the receiver again. Two of my favorites are here:

and here:

While both videos SEEM idiot-proof, the makers of each have apparently not yet dealt with the likes of me. There are nuances that I failed to grasp, and these caused me grief when I set about removing and replacing my own takedown pins.

Allow me to explain…

Trouble removing the front takedown pin

I closely followed the instructions for removing my rear takedown pin: here you can see the pin extended, but still held in the receiver by its retention pin and spring.

To move the retaining pin out of the way without disassembling the rifle, you can fabricate an official “U.S. Army takedown pin removal tool” by filing the short end of a hex wrench to a sharp point as shown:

As explained in the video above, you then insert the sharp point under the retaining pin, push down, and rotate the takedown pin to move the retaining pin channel clear.

You now just pull the takedown pin out of the lower receiver. All too easy!

Unfortunately, neither video addresses removing the FRONT takedown pin. Since the front and rear pins are very similar, I decided to use the same technique.

It works exactly the same, except for one key point: when the rear takedown pin is removed, its retaining pin is contained in the receiver.

However, when you pull the FRONT takedown pin from the receiver, its spring-loaded retaining pin is now open to space and will attempt to launch itself into another dimension, never to be seen again.

My plan was to slide a clevis pin into the receiver as I removed the front takedown pin, trapping the retaining pin in place. Brilliant concept, but poor execution on my part–I didn’t apply steady pressure on both sides and zing! the retaining pin took flight.

You can avoid losing YOUR retaining pin by the simple expedient of wrapping a gallon Ziploc (r) bag around the front of the receiver. You can see through the bag to work, and it will capture the forward retaining pin if it tries to escape.

If you’re like me, you’ll be convinced of your ability to control the spring and retaining pin and won’t bother with this simple precaution. If so, I’ll wait while you look–in vain–for your lost retaining pin (it probably landed next to mine).

Pro tip: if you lose your retaining pin and don’t want to wait until the mailman brings a new one, a spare roll pin (like the one that holds a gas tube) will work as a replacement.

Trouble installing the rear takedown pin

In any case, now that we have both of the old takedown pins out, it’s time to install the new ones.

The clevis pin trick in the first video worked flawlessly for installing the forward takedown pin. This time, though, I had the Ziploc bag backup in place, just in case.

The other video has you use an old takedown pin (instead of a clevis pin) to install the rear takedown pin.

I learned that one inserts the old pin PART WAY from left to right, enough to push it against the retaining pin, then uses one’s modified hex wrench or implement of choice to press the retaining pin down, out of the way, into the receiver.

In this next action shot (pardon the blur but there was SERIOUS WORK going on here), I’ve pressed the retaining pin partly out of the way–despite the spring pushing up on the pin–and you can see it’s wedged there by the old takedown pin.

So far it’s working just like the video.

However, shortly after I took that picture, something bad happened.

To be fair to the man, he clearly says you don’t want to push the old takedown pin all the way in to the receiver. Sadly, I didn’t appreciate the importance of this advice until I let that very thing happen:

As you may be able to see from the photo above, not only did I accidently push the old pin all the way into the receiver, but through extreme bad luck I also allowed the retaining pin to lock it into place—backwards.

Because the rear takedown pin is now trapped INSIDE the lower receiver, backwards, you can’t use your hex wrench tool to get at the retaining pin, nor move it so you can.

I’m sure there’s an elegant solution to the fix I found myself in, but after puzzling over it awhile I admitted defeat and went with the time-honored “brute force” method of removing a stuck takedown pin:

Dremel cutting wheel to the rescue!

(let us never speak of this again)

Turns out I had a better tool for replacing a rear takedown pin available all along.

No, not the clevis pin: while it works great for the front takedown pin, it could also have trapped the retaining pin and gotten stuck in the rear receiver–and because it’s made of tougher material, would’ve been even harder to cut out.

The tool I’m talking about–the one I should’ve used in the first place–is the butt end of a humble 1/4” drill bit.

It has no gaps or channels for the retaining pin to snap into if you fumble the installation (like I did). Here you can see the retaining pin held down in the receiver by the drill bit.

It was easy then to push the drill bit out of the way with the new takedown pin.

A twist of the new takedown pin allowed the retaining pin to snap into its channel.

You may notice a bunch of aluminum dust on the receiver (from cutting out the old rear takedown pin) in the last few pictures. Don’t worry; I did clean all that off before reassembling the rifle: not only does it look ugly, but I didn’t really want those metal shavings collecting in my trigger assembly. Compressed air and aerosol gun cleaner, along with a toothbrush and a handful of cotton swabs, took care of that.

So to recap, you can idiot-proof the techniques shown in these videos by remembering these important safety tips:

  • when removing/replacing the front takedown pin, wrap the front of the receiver in a Ziploc bag to catch the retaining pin if it manages to escape.
  • when replacing the rear takedown pin, use the butt of a 1/4″ drill bit to hold the retaining pin in place, then push the new takedown in, displacing the drill bit

P.S., with the new takedown pins the fit between upper and lower is much improved–so in the end, I felt all the drama was worth it.