Ron
Have you tried using 308 brass?
I found it easier to make 6.5 [Noble and Creedmore] with 308 instead of 243.
No doughnuts. And it is cheaper.
The only problem that I can see with this method is that it would seem that the brass would come out short, with a large gap between the end of the neck and the end of the chamber. Excess gap space.
al