Kind of late to the game here, but this is something that piqued my interest since I am not building an Iron Ridge upper & lower AR 308. How can Iron Ridge represent that the damage was "Normal in all AR rifles" when they claimed before that the " never had this issue with other builds". If it was never an issue before, how did something they had never seen before become the new normal? That damage appears to me to have been caused by the BCG extending back into the buffer tube, slamming against the buffer retaining pin. That is NOT normal, and is rarely seen - only when someone tries to mate an AR10 with a DMPS upper/lower/BCG, where there is a gap between the upper and lower receivers. I know Iron Ridge was selling both Armalite and DMPS style lowers around the same time, and began upper production with the DPMS style. Is it possible you had an Armalite lower (maybe marked as a "D"), married to a DPMS upper? As for the "normal" comment, that bothers me a great deal. Frankly, I have had great dealings with Oliver at Iron Ridge, and am more than a little shocked at this comment coming from anyone at Iron Ridge. I am not implying that is what they told you, but one would think that a company deep into the AR market would know that the guys buing their components have a touch more experience with these platforms than the average buyer.