Awhile back I built my brother a rifle with a spikes lower and a psa upper. I bought the spikes lower from a guy would had built the lower. So I am not sure of parts that were used in the build.
Today my brother calls me and says the rifle will not shoot. He breaks it down and found the buffer retainer and the its spring had came out of the hole. Somehow the spring worked its way into the bolt carrier group and was causing problems.
The castle nut is staked and the buffer tube was screwed in to where it covered the shoulder of the retainer.
What would cause the buffer retainer to pop out?
Trying to get my brother to send pics.
This is why you do not build with parts of unknown quality.
I am going to guess the tube is out of spec and needs to be replaced. Out of spec as in not covering the buffer retainer enough.
In my San Antonio class a few weeks ago someone had a lower where the buffer retaining pin hole was drilled incorrectly. This caused issues with the lower receiver extension and it was barely engaging the lip. I suspect that it may have been the case here and it worked loose because it wasn’t engaging the retainer properly.
THIS! You read a lot of posts where guys buy just any lower they can get for a bargain to use for their build. This kind of crap is why I’m fanatical about which lowers I’ll use.
I just had this issue putting together a couple lowers. The BCM extensions I had fit these (AXTS) lowers perfectly, with just the right amount of engagement between the extension and retainer. The Vltor A5’s, not so much. They were just barely engaging, and I could see a possibility of the retainer popping out after some wear and tear. But rotating the extension one more full turn would go too far, so I made a small modification to the extension tube. Now I’m getting excellent engagement. Everything appears to work great, and only took a moment to do
Make sure the tube is not turned too far in or the upper will not fit onto the lower. Looks like the tube edge is sticking out some from the receiver in the pic.
