Measurements are good for te taper crimp die. I figure bullet diameter of 0.356 + 2 x case mouth thicknes of 0.011-0.012 = about 0.379".
Somethign else to consider - a light bullet seated long vs. a heavy bullet seated short will result in very different bulges in a tapered 9mm case.
Also, drop the case into the hundo upside down. This can tell you if the problem is neat the case mouth or the case head.