Lots of info out there on this subject, and differing opinions...
I found a way to increase neck pressure when loading WSL .351 rounds, and I was wondering if the tighter neck might make the pressure too high.
The rounds chambered and ejected perfectly when loaded my "old way", but there was never enough neck pressure to keep the bullet from spinning (by hand) in the case. The powder (IMR 4227 compressed slightly) held it from pushing in and the crimp kept it from moving out.
As a test, I ran some cases (357 Mag) into a 9mm crimp die before loading the bullet, which tightened the neck for the length of the bullet, then I expanded the case mouth slightly, then loaded the powder and bullet, and crimped with the .38 sp die. Seems to work great. Dummy rounds load and eject. I'll test the rounds Monday with a chronograph.
I don't know how these rounds compare to the original rounds as far as pressure.