This past week I went shooting with a friend of mine who after a few shots called me and showed me his bolt head (see below). I need some thoughts as to what might have caused that.
It is a 308 caliber. My friend only put through this rifle less than 1000 rounds. We looked at all his fired cases and we observed no signs of unusual pressure. I don’t recall the exact load he was firing at this particular time but nothing that he didn’t use prior. Is this something that might have happened all of a sudden or over time?