I had a buffer retainer defect while at the range today. In attempting to figure out what the issue was (is) I noticed the buffer itself, at the end that contacts the buffer retainer is not round all the way. It was designed with three flat sides. I am supposing that afte firing for a bit, that one of the flat sides of the buffer worked its way around to the bottom where the small post of the buffer retainer is and thus did not engage the buffer retainer completely and consequently jumped it.
Anyone with this issue? Is this a design flaw?
It’s suppossed to have flats. There is no design flaw. Something isn’t right. The buffer shouldn’t even touch the retaining pin when the action is closed.
The back of the carrier pushes the buffer back and takes the tension off of the retaining pin when the actions are closed.
Thanks for your reply. It all looks normal. Guess I’ll pop in a new retainer and see what happens.
Is the retainer damaged?? Can you get pics of any problems?
The retainer is sheared partially at about a 45 degree angle at about the top 16th of an inch, just one side.
I see what I can do about a picture.
What are the flats for anyway?
The flats are there to prevent the buffer from having too of a seal in the receiver extension/buffer tube.
I’ve never seen a retaining pin bend like you describe. Ususally the pin’s hole in the lower gets egged out from getting banged by the buffer face.
What’s your email, I’ll send a picture.
I pm’d it to you. Can you attach it to your reply here or host it? I’d like Iraqgunz and the gang to be able to see it.
Post the photo here.
I have a crappy Bushmaster too and I’d like to see JIC.
Best I could do was an email to your ATT mail
is this a collapsible stock?
yes ,Magpul UBR
The pic is blurry and only of the damaged pin. I’d kinda like to see the buffer area of the gun, or maybe the back of the bolt group in the upper.
The damage is done to the pin, but the question is why. The retaining pin should never have enough force on it to do that.
I’m wondering if the bolt carrier didn’t smack it some how. 
Pin pic?
I’m wondering if when I installed the UBR, I didn’t tighten the tube completely. I say that because I noticed that when I was checking it out, I noticed there was a small dented, not that bad, on the tube in the area of the buffer retainer pin. Upon reinstalling, that little dent area was a half turnpast when it was. In other words, the tube was not tightened completely allowing the buffer retainer to move up further that it should have. Pics to follow.
Hope this makes sense
pic attached
try this again.
That’s possible. I’m not familiar with the UBR. It has a proprietary tube doesn’t it?
Pic #2 almost looks like there’s damage to the buffer retaining pin hole.
Is the buffer tube just barely touching the edge of the retaining pin (when its in)? It does look like maybe you should have given it one more turn.
UBR does have a prop tube but it fits exactly as the OEM. I believe the top corners of the second thread have been knocked off. Crap, I hope thats not going to be a major issue in the stability of the buffer retainer.