Okay, I found it...now here's my dilemma:

So there I was, mounting a VLTOR stock with a Mil-Spec buffer tube to my AR.  After I removed the flange (?) the rear receiver-retaining pin spring went screaming across the room.  I eventually found it, and as I retrieved it from the carpet that seemed so insidiously wishing to hide and claim it, it became snagged and as I unsnarled it from the evil pile of my carpet it had a kink in it.  

I snipped off the offending ~ 3/16” section.  Then I stretched the spring and re-installed it.

I checked for a firm detent from the pin, and the feeling was positive that the spring forced the detent to lock against the stock-retaining pin.  I experimented at the range, and after three magazines emptied in ~ 4-minutes of fire (I was not going for accuracy), my “shock and vibration test” did not result in any loosening of the rear receiver-retaining pin.

Question…is this a safe weapon, or will I see a bolt through my forehead in the future?

Thanks,

Ed

Yer probably good for now...but it will always bug you....you know it will....so order some spares and a few other spare parts to make the order worthwhile and then install it at your leisure.....

you won't regret not having to wonder......

Its a .95 cent part, I would replace it.

Or you change you fireing technique and hold your rifle sideways like they do in the movies

I'd say your gun is perfectly safe........but getting spares is never a bad thing.