It sounds like your die is sizing the necks down too small if it's pulling that hard. Also do you lube the inside of the necks? I had a FL die that sized the necks down so much that they split on the second or third reload if they weren't annealed. Sent it back to RCBS with a couple of fired cases and they honed it out.
You also may want to take the stem out and gently chuck it in a drill and polish the expander ball.
Best suggestion here. Along with setting up the expander for the proper depth. Guys saying you need special bushings and chidt are clueless. Unless you are shooting benchrest, our of a benchrest rifle, and demand some kind of extreme precision. I'm assuming not, since this is a "big game rifle" reloading forum. A regular ol RCBS die will suffice. That is all that is even required for most precision longrange shooting as well. I watch guys like the OP struggle, because they think they need unnecessary chidt. Keep it simple and you'll have less problems..
