Quote History Quoted:
Buffer retainer hole drilled to far back? Are there noticeable wear marks on the buffer retainer pin, like the buffer is hitting it?
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Correct answer, since the dents on the outside of the buffer face are from the buffer tagging the buffer retainer pin. Hence the back of the carrier is not caming the buffer face off the retainer pin as the upper is closed, and causes this wear to the outer edges of the buffer face.
The best solution short of band-aiding, is to sent the lower receiver back for a replacement (one which the buffer retainer channel is correctly located instead).
1. is the buffer tagging the buffer retaining pin since it channel was drilled too far back in the lower receiver.
2. is burs on the back of carrier edges.
3. is a Bur on the back bottom of the U channel of the carrier