I’m installing a Palmetto State Armory lower parts kit into a stripped Spikes lower receiver. This is my first build from a stripped lower. Everything seems fairly straightforward, except the rear take-down pin and detent pin. I installed the rear take-down pin, slipped the detent pin (both ends are equally pointy) and spring into the hole on the rear, and installed the locking plate and castle nut. Everything seemed to go together as expected.
However, when I checked the rear take-down pin I noticed that it did not seem to lock into place when fully in or out. The detent pin just barely prevents the take-down pin from falling out, but doesn’t seem to stick out far enough to make contact with the dimples on either end of the take-down pin slot.
In looking at the detent pin, it seems like it should pass all the way through the hole from the rear, and press fully onto the take-down pin. But my detent pin seems to only peak out of the hole, preventing it from fully making contact with the take-down pin.
Can someone confirm, is the rear detent pin supposed to be captured inside the slot, or should it be free to fully exit towards the front into the slotted take-down pin?
Looks short. How is your pivot pin’s detent? I assume it’s gtg? did you by any chance notice your TD pin’s spring being a bit shorter that the Pivot pin’s?
It could be a weak or missing spring, debris in the hole, short pin or improperly drilled hole or a combination thereof. Pull it apart and see what’s going on
The front detent seems to be working just fine, so I pulled it apart and swapped the detent & spring to the rear to see if that would help. It didn’t change anything. Should the front and rear detent springs and pins be the same dimensions?
I’m kinda thinking that the hole in the lower receiver was not drilled correctly, but I don’t know if the hole should be drilled completely through, or if it should retain the detent pin like it is in the photo above.
Maybe I should ask this in another way. If you pull your rear take-down pin out, would your rear detent stay in the hole (like the photo above), or would the spring push it out?
It would push it out completely. not sure what the correct drill size is, but you probably just need to use one to finish reaming the hole all the way through.
From my experience, it is usually some left over anodizing in the hole. Ream it out carefully with a drill bit so that the detent will pass all the way into the takedown pin hole. After that you should be GTG.
The detent pin should fall right thru the hole. I just did this with a Mega lower (not ‘assembled’ yet) and a detent pin from PSA. The pin passed into the hole for the TD pin.
Your detent pin is being held up at the end of its travel. You might be able to tap the pin, to break thru the other end, or drill it out, carefully.
Did you rotate the rear pin around so that the detent will catch the groove in the pin?
You probably knew this but you have to put the takedown pin in place, then drop the detent into the hole, followed by the spring. Then slide the endplate down to compress the spring, then tighten down the castle nut. Last step is to pull the takedown pin out just a little and spin it a little one way or the other so that the detent will catch in the groove.
Ya, I did that, but thanks for the suggestion. Sometimes it really is a “Doh!” moment, just not this time.
Thanks, this confirms what I was suspecting. I will take a look and see if I can use a small drill bit with some finger turning to gently push through the black coating.
Yes, definitely turn the drill bit by hand since you just need to remove flash or very little metal. You’re almost guaranteed to bubba the hole by using a powered drill.
BAM! Problem solved. Ran a 3/32 drill bit through the hole by hand and cleared a bur that was hanging things up. the detent pin drops fully into the slot on the take-down pin and holds it in place as it should. Thanks all for the help.
