Its hard to say that neck sizing or FL sizing is better over the entire range of differnet situations out there. Let me explain.
If I have a 6mm-250 Rem that I use with a moderate pressure load for target comp shooting, I would recommend neck sizing because the low pressure combined with the generous body taper on the case design will allow this and still offer good chambering and good extraction.
On the other hand, say your working with a round that is used at upper end working pressures and is in a case design with minimal body taper, you will want to at least partially FL size these cases.
Partial FL sizing is when you run the case up into the FL sizing die as far as you can but stopping just short of touching the shoulder of the case in most instances. What this does is size your necks and also slightly reduced the diameter of your case body to insure that the round will chamber and extract well with the higher pressure loads being used. If you do not reduce this body diameter slightly, after a few firings you will start to notice the cases being a bit difficult to chamber as well as getting sticky extractions. Just reducing this body diameter slightly without touching the case head will insure easy chambering but also keep that shoulder where it should be for accurate loading.
In rounds such as my Allen Magnums which have very little body taper and are designed to work at the upper range of working pressures for their parent case designs, I recommend just very slightly bumping the shoulder. BY this I mean, setting it back no more then a thou or two as well as reducing the body diameter just slightly as well. This is basically FL sizing but not to the degree that the shoulder is relocated as it would be with conventional FL resizing.
This is a technique that must be practiced and learned and checking sized empty cases in the rifle for chamber feel while setting up the sizing die is critical to getting it right. What you want is the case to go from just a snug fit in the chamber needing a slight bit of force to close the bolt to the bolt closing easily.
The trick is to hit it just right. The difference is generally less then 1/8 revolution turning the die down into the press, often around 1/16th of a turn is perfect. You have to go slow, you have to pay attention as well but once you get it, you will get the benefits of a neck sized case as far as accuracy and long case life is concerned and also the benefits of a FL sized case in easy chambering and extraction.
I would also agree with Bounty Hunter on this one that if your using Standard dies, you will size your shoulders and necks down much more then needed but if you are careful not to agressively set that shoulder back with FL sizing you will be fine.
In my experience, FL sizing with the proper dimensioned dies and JUST barely bumping the shoulder has produced the best results for me, especially in high pressure, min taper case designs.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Farther, Faster and Flatter then ever before.
Web Page: www.apsrifles.com