To follow after bearhunter's comment, might want to understand that in a full length die, by the time the case gets high enough to press back on the shoulder of the case, the neck of the case will be fully into the neck sizing area, which is smaller than standard - that is why there is that expanding ball on the decapper stem - it will normally be inside the case when the outside of the neck has been sized too small - as the case is pulled out of the die, the neck is dragged over the expander ball and opened up, from the inside, to the correct size. That way, neck thickness does not matter as much - all cases are going to come out with the same inside neck dimension.
So, when you do go to re-size those brass, remove the de-capping pin, but leave the expander ball. It can be set a bit higher than normal. If you remove the stem completely, all of your case necks will be too small inside diameter - not likely you will be able to seat a bullet. On a fixed one-piece unit like some Lee dies, I do not think it can be done, but I have never tried - I have done so several times with RCBS dies, which have removable de-capping pins.
I have read in more than one place that you are looking for about .002" neck tension - in other words, the ID of the neck will be about .002" smaller than the OD of the bullet - inserting the bullet stretches the case neck that last little bit. There are some that will remove the stem completely - resize the cases which results in neck ID being too small, then re-install the expander ball and open the necks by setting that expander ball a little lower than normal and opening up the necks while running that case up over the expander ball, and then back out - not running the case neck far enough to enter the neck sizing area. It is claimed that opening the case neck on the ram's up stroke has less chance to stretch or deform the neck or shoulder, resulting in better concentricity, compared to "normal" procedure of pulling the neck over the expander ball on the ram's down stroke.