Ted,
I don't think the dents are caused by that irregularity. 6'OClock from the pen line is the knife edge between the two feedramps. I get them on mine, but not as severe as your photo. If that case has been fired before, the smaller dent near the larger ding is likely a previous firing that has fireformed under pressure to the shape of the chamber. So fireforming is sort of fixing them for you, but not completely. By the time the case is stripped from the mag and gone past the knife edge it's lining up pretty square to the chamber, so that irregularity probably does not even touch the shoulder.
As for the irregularity, wondering how metal gets chipped off at that spot and can only think of the bolt slamming into it as part of normal cycling. Especially if the carrier is released without a round to slow it down. Less likely cleaning rod damage, but maybe if the barrel was predisposed to crack at that spot.
I don't think the dents are caused by that irregularity. 6'OClock from the pen line is the knife edge between the two feedramps. I get them on mine, but not as severe as your photo. If that case has been fired before, the smaller dent near the larger ding is likely a previous firing that has fireformed under pressure to the shape of the chamber. So fireforming is sort of fixing them for you, but not completely. By the time the case is stripped from the mag and gone past the knife edge it's lining up pretty square to the chamber, so that irregularity probably does not even touch the shoulder.
As for the irregularity, wondering how metal gets chipped off at that spot and can only think of the bolt slamming into it as part of normal cycling. Especially if the carrier is released without a round to slow it down. Less likely cleaning rod damage, but maybe if the barrel was predisposed to crack at that spot.