It's not an issue with the die per se. The hardness of the case in the area where the new shoulder is formed is harder than a neck/shoulder area is on a factory case. You can try annealing the case in this area prior to forming. Just be careful that you don't let the base get too hot. If you've never done annealing before, read up before attempting it.
Working the brass, ie: forming and resizing, hardens it. Annealing softens it. Only the neck and shoulder area should be annealed.

Or you can do this.
Take .005 off the top of your shell holder. Mark the shell holder for this purpose only. Use a good lanolin based lube like Imperial Sizing Die Wax.

You could also buy a set of the Redding shell holders that are in .002 increment different thicknesses, but they are pricey.
Redding Competition Shellholder Set #1 (308 Winchester 30-06

Finally, anneal the case necks when you are finished reforming them. They will crack if you don't.

Graf & Sons has new Prvi 7.65 brass for $60/100. After you reform/trim/anneal 100 cases, you will probably wish you just bought new ones.
Graf Sons - PRVI PARTIZAN BRASS 7.65x53 ARG. UNPRIMED 100/BAG