I just bought an 18" American 30 barrel. I bought some 30 Herrett Pacific dies and found the expander did not fit in the 6.8mm case.
So, I ran some cases into a 300 Blackout die to enlarge the neck being careful not to run the case in too far.
I then ran the cases into the 30 Herrett die just until I felt some shoulder resistance. The shoulder got a bit sharper and I stopped.
I seated a bullet into an empty case for testing. I forgot I have to trim to 1.620" and will do this next.
I wonder why the chamber was designed to be trimmed at all? Why not just size and load?