I just built my first lower from a Rock River Arms stripped lower, a Rock River Arms lower parts kit, and a DPMS panther A2 buttstock kit.

 

Everything went great, complete success in around 30 minutes, no problems, only launched one spring but found it. Used two different build write-ups on AR15.com, and it was easy.

 

However, the very last step was the rear takedown assembly, with the rear takedown pin, takedown pin detent and takedown detent spring.

 

It does not appear to me that there is a hole in the RRA lower for the rear takedown detent and spring. I've looked and looked, there is just no hole for the detent pin. SO, the takedown pin sort of slides in and out, not retained at all.

 

Some of my AR-based rifles have takedown pins and pivot pins that just slide in and out, and some (like my Colt) which have both front and rear pins retained.

 

Is the hole missing from the RRA lower? Do I need a different style of rear takedown pin in this case?

 

Thanks.

Did you put the stock on? The hole is in the rear.

 

Ha! That explains it! I'll fix it tomorrow. Thanks very much.