Hate to bring in another variable but how about your crimp.
Taper or roll?
I prefer a firm taper crimp on 9mm using lead or jacketed. The one time I tried Berrys I found that the same crimp that I used on cast lead and jacketed deformed the plated bullets. Once I reduce the crimp I got better results.
One other thing, are you doing a separate seat/crimp? I had a similar problem using XTP bullets that were deforming trying to do both at the same time. As soon as I started seating then bring them back through a separate taper crimp die things got better.