I bump the shoulder on my hunting rifles, full length the ar, and neck size the varmint guns. Gotta mix it up.

I neck size only. I have had neck sizer dies made for all of my toys, and I anneal as needed, and will only full length when needed. New cases are trimmed and full power loads are used for forming to chamber.

I keep reading these posts about you guys bumping the shoulder a bit. Now the way I understand a sizing die to work is that it is basically a mould that reforms the brass back to SAAMI specs. So in "bumping the shoulder back a bit" you're not very far from FL sizing. About the only thing you didn't size is the web area of the case which is done by camming the ram against the bottom of the die. Backing a FL die out a bit is not neck sizing - it is partial sizing.
If I'm incorrect I want someone try and explain how they neck size or bump the shoulder in a FL sizing die without resizing 95% of the case.

You got it. "Neck Sizing" by kissing the shoulder with a FL sizing die is a partial resize. "Neck Sizing" by bumping the shoulder with a FL sizing die is actually effectively a complete FL size.

There ARE neck sizing dies which don't touch the case body at all. These are typically labeled as such - Neck Size dies.

Bronko,i often thought the same way about "Bumping'.
I just could not understand how you could do it?
I have neck sizer only dies.
With these i seldom size the whole neck !

WE must have been taught by the some reloading god!!! If I feel that I am going to ONLY neck size a particular round for a particular rifle, I will buy a true neck sizing die to that set of dies and I have it. I own about 10 true neck sizing dies so far. All bench/speciality rigs.