You'll also see comments like "I neck size until they're a little snug so then I use a body die (or FL die) to squeeze them a bit so they chamber smoothly again." What this indicates is from firing to firing the fit of neck sized brass to the chamber does evolve.
The reason Cortina and those guys FL size is so the brass fits the chamber the same way every firing. In the super accuracy/precision realm consistency is the name of the game.
That explains a good part of it (for me), but I'd bet a dollar to a donut they're using some pretty pricey custom dies too.
My own method is the Lee Collet die used with Redding body dies and Forster seaters. One of the main attractions to using that method was to escape the necessity of lubing cases during every reload, but after using these dies for a while I got to where I go ahead and run everything into the body die each time I use the cases whether they really need it or not (because I'm too lazy to check them and keep track of number of firings among other things, mainly). So much for avoiding lubing cases.
I'd say I am accomplishing the same thing they are in terms of sum result, except I'm not spending hundreds of dollars on precision dies. Since I like to use run-of-the-mill sporter weight rifles for the most part and don't expect to ever take a shot over four hundred yards anyway, I doubt that spending beaucoup bucks on Whidden or even finer dies would be worthwhile. But then again, I haven't tried it.
