I will buy what he said, I'm not buying why they rounded the reamer. And, why the No-Go should fit. I'm not a Dasher shooter so I may be way off here. It seems to me the rounded junction would increase brass growth, and they should call it something other than Dasher. Perhaps as @mikecockcroft suggested "Weatherby Dasher". Perhaps the rounded junction is to reduce donuts. Perhaps it will shoot fine once you get fireformed and trimmed. Perhaps something else. I would be extremely disappointed and the barrel would go back. I'm interested in what other experienced Dasher think, I may be all wet.He said that their chambers are slightly rounded (i.e., not as angular as the shape of virgin brass) at the neck/shoulder area, so it's no surprise that the brass would take on that shape. That made sense to me, but it seems that you and Aaron aren't buying it.