If that were true then neither crimp would be satisfactory.My Lee 3 die set is a combination of both, depending on how you adjust them.
There are two crimp shoulders in our bullet seating dies. The first shoulder applies a slight taper crimp and the second shoulder applies a full roll crimp. The closer the die is adjusted to the shell holder the heavier the crimp will be.
Slight is right.
I have a set of Lee Carbide Dies in .45 sitting on my desk this very moment that I am looking to dispose of becaue they won't crimp worth a damn.