Another good read is a article called IIRC - "Tales of the old Houston warehouse". After I read that I never uniformed a primer pocket again.
Is your 300WM chamber SAAMI spec? If so then don't turn much more off than .001". All chambers are different, especially the neck. For instance I had a DPMS 308 that had .011 neck expansion, which is ridiculously large, I was getting some split necks on the 2cnd firing so it would have been useless to turn necks for it, not that I would for a rifle like that anyway. Normal neck expansion is usually .007-.008". Still a lot IMO but neck turning could be beneficial still.
Anymore I'm only turning necks for my customs which have tight neck chambers, .002-.003" expansion and never get a split neck. Between annealing on my Benchsource and the necks being turned within .0002" of each other, there is almost no difference in neck tension. The last ladder I did produced a 5 shot .9" group at 400Y and all five were .1 grain different in charge weight.