Neck sizing with the Lee collet neck sizing dies eliminates the need for lubing the casing. However, if you are using any type of neck sizing die that has an expander ball that gets dragged back out through the neck once the neck has been resized, then you should use a lubricant on the inside of the neck. Dry lubricant is less of a mess, but I still like to clean that out to make sure I have a consistent "grip" on the bullet and no dry lube left in the neck.
If you have a Redding Type S bushing style neck sizing die and are using the TiNi bushings or have carbide bushings and your bushing size is just slightly under your chamber neck size, you can probably get by without the expander ball and thus you won't have to lube the inside of the casing neck at all.
Even though you use your casings in the same rifle, you will probably find that you will have to full length resize your casings eventually. My epxerience with factory chambered rifles is that after about 4 or 5 firings, my casings need to have the casing body bumped or the shoulder bumped back just a wee bit to keep the casings from being difficult or impossible to chamber. It is not much fun when you take a shot in the field and cannot get the fired casing out of the chamber. Don't ask me how I know that /ubbthreads/images/graemlins/smiliesmack.gif /ubbthreads/images/graemlins/angry-smiley-055.gif /ubbthreads/images/graemlins/smiliesmack.gif