This is how I form Whisper brass. It is pretty easy, and I have never split a neck. The reason is I am not trying to expand a .22 caliber neck to 30 caliber .... rather I am down-sizing the former case wall of the .223.
A - a .223 case
B - I cut off the .223 case at the neck. I have used a Dremel tool held in the hand. I have also used a cut-off tool mounted in a drill pess with the table set to the correct height. Then just hold the base of the case on the table push it into the cut-off wheel and rotate. That method is really fast.
C - A photo of the .223 after the old neck has been removed.
D - I then trim to 1.350" I have seen a wide variety of OAL case measurements. I have seen 1.350" all the way up to 1.400" .... I have found 1.350" works well for me (your mileage my vary)
E - Then I press it into the sizing die, creating the new neck and shoulder. I use Redding dies, I do not use the smaller (7mm) expander ball, as there is no need to since I am sizing 'down' and not sizing 'up'.
I find that this operation lengtens the case a little - so I trim again.
Then I chamfer the inner and outer edges, clean the primer pocket (ream the primer pocket if I am using mil-spec brass). If you have a tight chamber, you might want to neck turn to the proper brass thickness, but I don't need to for my rifles. Lastly, I toss the brass into the tumbler to remove any resizing residue.
Sounds like a lot of work, but the Whisper is still considered a wild-cat and wild-catting a cartridge takes time and effort. But it only needs to done once (per cartridge).
After that, I neck-size only for bolt actions, and full-length size for semi's
Threaded Mode