Are you chamfering the inside of the case mouth?

Also do you brush the inside of the case neck with dry lube/motor mica?

The chamfering alone should allow for the bullet to seat without much force.

The motor mica helps prevent case stretching when the expander ball passes through the neck.

Check to make sure you are not touching the crimp in the die before the bullet is fully seated.

I hope that this helps. 30-30 is very easy to reload.

Bruce