I trim the cases, turn the outside of the necks for a uniform neck wall thickness, and polish the insides with fine steel wool.
I have also radiused and polished the expander ball, and leave it a little loose in the die. I have to full length resize and then some for my 25 wssm shoulders.
I set the bullet on the case neck, as straight as I can, and seat it.
My runout on my case necksand loadedcartridges is about .002", every now and then .004"
I havn't messed with the RCBSshellholder spring..................yet.