Nk v FL I'm not ready to quit neck sizing. My 300UM Surgeon is a honest 1/4" gun on an average every day. I neck size. I only FL size when case grows too much or with annealing. (Every 4-6 firings) I never have a tight bolt or jammed case. Not once if pressure is right.
I have a perfect case in point. I recently bought a 24" 224 Valkyrie barrel from arguably one of the best makers around. I spent $790 five months ago. 240 rounds thru it, 5 powders, 6 bullets and my 30/30 is a better shooter. I use new Starline brass. After my first range trip I measured the cases. Every one grew .008" in lenght and .006" to 009 in diameter in different places. The lenght can be dealt with using a FL die but the diameter is another beast. So I FL resized several once fired cases. And they shot like ——/. The resized OD on the cases was exactly the same as the new Starline brass, and its not a small base die, which would be worse. So I neck sized. If bumping a shoulder for .002" clearance is required for accuracy how can sizing a case OD back .005-.009" only to have it expand back .005"-.009" for every firing help accuracy? It doesn't. I spend a lot of money on chambers. If one does not know the relationship between their chamber and OEM dies they are leaving accuracy on the table.
I fit, build or buy a die to be .002"/.002" (lenght and OD) to my chambers. This is very simple to do with any tapered case using the chamber reamer and a blank die body from PTG. You could sort of do it with a FL die but you wouldn't go in far enough to move the shoulder.
Using a SAMMI FL die, which means min spec FL OD die, in a custom chamber can work harden your brass if you move it .008" each time.
IF you have a chamber reamer that cut .002/.002 over min SAMMI then by all means FL every time.
There are no absolutes in what we do. So with some qualifications yes, full lenght size. However to say it as the be all end all to Precision loading is just wrong.
Has anyone noticed on the Valkyrie threads there is a pretty common load note from a lot of people? That is that neck sized fired brass is strangely 50% more accurate than new or FL sized brass? That has been my experience too.
As far as the competition crowd goes, many of the people I know use dies made by their smith or they send out fired brass to have custom dies made. Why?
When you have $10k in a gun and glass, $300 in match dies makes a lot of sense. And you can measure the difference in inches @ 1000.
Just my opinion.
The last part is the only valuable information. You said it. No one winning at the elite levels of competition are neck sizing. It becomes even more important with a hunting rifle because you never know when your lack of proper sizing is going to cause a round to stick in the chamber when you need a follow up shot. I think Erik might know what he is talking about. If the argument turns from off the shelf FL dies to custom dies then maybe we would actually have a discussion. I can assure you over the life of a rifle with loads properly developed with FL sizing the FL sized will have a smaller average group size. NK sizing in an ar makes even less sense than in a bolt gun. That is just begging for a stuck case in a chamber.