Are you asking if you should neck turn before or after fireforming?
I shoot the Dasher.
1. you do not normally neck turn the brass. Fire form the brass.
2. If you do not know the neck diameter of chamber, use the fire formed brass and load a bullet into an Empty brass and try chambering the shell,
if it chambers without leaving any sever marks on the neck you're good to go.
3. I have not heard of anyone having to or wanting to turn necks for the DASHER.




























