Can fl dies be set up to neck size only? The instructions that come with the rcbs fl dies say that it can be done but don't say how.

Yes, i have most of my FL dies set up this way. I back the FL die out about 2 turns. Then smoke the case necks and shoulders. I then proceed to turn the die in about a 1/8 turn and run it in to the die. I continue this until i just see it smudging the shoulder.

HTH

Smoke the neck and shoulder or use magic marker to see how far down on the adjuments you are at. It is a trial an error thing to get it where you like the sizing at.

Hcliff

Yes you can but only kind of. The FL dies start squeezing the base of the case by the time it resizes the neck, the brass has to go somewhere & that is up. Even though the FL die does not touch the shoulder it will move forward.If you set it up to FL the shoulder gets pushed back so its not a problem.

Special Neck Dies only size the neck not the body. If you really want to neck size on a regular basis get neck dies.

With most cartridges you end up FL sizing which is what you should do anyway. I set the die by bolt feel and not smoking.

Cases with a lot of body taper and long necks such as my 6MM Rem International (.250 Savage case) ccan be done and they work very well. Even then only part of the neck can be sized. This is quite suitable for target loads.

Simple and easy to do just place your press at full swing with the shell holder in place. Run your FL die in until it contacts the shell holder then back it off 1/16". It is still best to have neck sizer only die to eliminat over working the brass. The FL sizer die still resizes the brass except for that last 1/16" before the case shoulder contacts the die. Some cartridge cases tend to streach when neck sizing with the FL die and will chamber hard. The neck sizer only die eliminates that problem.
You do keep head space on the shoulder by neck sizing with the FL die, but brass life is no better because your still over working the brass.

Or, you may want to look at the Lee neck only collet die... great tool, very accurate, and not at all expensive. I use them, and they are especially useful on rifles such as my old 7 x 57 mm Mauser which has some headspace problems... Not really answering the "gist" of your post, but this could be of interest to you.