I built my AR a few months ago but haven't shot it much. A few weeks ago I noticed it coming loose at the range after a few hundred rounds. I'd just push it back in (came about 1/4 way out). Today it fell out before I even started shooting and luckily I found it only to lose it again for good.  It's a Superior lower and I'm not sure who made the upper (bought on GunBroker). Anyone have similiar problems or better yet, fixes for this? It's really annoying. Thanks, take care.

Did you install the pivot and spring?

Just a thought.... shouldn't come out of the lower if they were installed right.

take the stock off and see if you still have the detent and spring

Just took it apart and found that the takedown detent and spring weren't there... Now I need to find replacements, anyone know where I can get them from?

Quoted: Just took it apart and found that the takedown detent and spring weren't there... Now I need to find replacements, anyone know where I can get them from?

Cheapest I've found are on Rock River's website: Parts #110 & 111 will set you back a cool buck.

www.rockriverarms.com/item-detail.cfm?ID=AR0172CB&storeid=1&image=lwrpts.gif&CFID=8195836&CFTOKEN=71404563