Noticed this when cleaning last night. End of the buffer is mushroomed out and dragging on the spring. AR15, home built and this was from a parts kit from PSA (and it was cheep). Gun has been working like a charm. I'd imagine its hitting the back of the buffer tube with a lot of force for some reason. It could be it was a very cheep part. Its an 80% lower build and I did not expect it to successfully work so stuck with the cheep parts.