It turns out the 6BRX and the 6 Dasher are very close in all aspects. one that is different tho is that the neck angle of the 6BRX is the same ass the 6BR. That means it is the easiest to fire form and tool up for. I went that route a couple years ago and bought 200 Lapua 6BR cases. I loaded them with some good 105-108gn target bullets so the bullets were into the lands 0.030 or so, 30gn of Varget and you are good to go. If you want, you can actually shoot in matches with the fire forming! Accuracy is great and nothing could be easier.
The nice thing about the 6BRX is the ballistics are virtually the same as the Dasher and the barrel life is way up there and velocity is typically 3000 or 3010 for good ballistics. I also have a 284 WIN F class gun and the 6BRX out-shoots it!