Get a Lee Collet neck size only die and the directions will give you the proper setting for your case. If you only have a full length sizer die, place the ram at full swing. Place a dime on the shell holder and scew your FL sizer die in until it contacts the dime and lock in place. Now you can neck size only with your FL sizer die while at this setting. Don't forget to back the deprimer stem back into the die before you make your neck size only FL die adjustment setup.

I prefer the neck sizer die to using the FL sizer die to neck size only. My reason is simple, the neck sizer only die does not contact the case body when it sizes your case neck. When you neck size only with the FL sizer die you partialy resize the case body also and that can cause unwanted case stretch.

I went through this exercise two weeks ago and decided to go with a neck sizer die. I opted for the neck sizer beacuse I don't like the process of adjusting the FL sizer die once in a while. For $20 I get myself a neck sizer and wouldn't have to worry about the adjustments.

Check this out: http://www.huntamerica.com/wwwthreads/showflat.php?Cat=&Board=UBB13&Number=520269&page=0&view=collapsed&sb=5&o=&fpart=1

Danny Boy

Here's how I set mine up. Take a fired case and mark the neck and shoulder with either a Magic Marker or Sharpee pen.
You could always smoke the case too, but I prefer the marker or pen.
Screw the die down until it touches the shell holder, then back it off about two full turns. Lube the marked case and run it though the die. Note where the neck has been sized. Turn the die a little farther down and run the case through the die again. Keep doing thin until you see that the die is just touching the shoulder. Wipe the case clean and try in the rifle. It may be just a bit snug, which is normal. Turn the die down just a hair, maybe about 1/16th of a turn and size the case again. (Don't forget to relube the case.) Wipe clean and try in the gun again. The case should slip in nice and easy. If not, do one more down turn (about 1/16th turn again)and that should do the trick. Lock down the locking ring and size away.
Paul B.