For reloaders who choose to retain the fire formed dimensions of their cases rather than resizing the entire case, neck sizing-only dies fit a definite need.
Although they only work the necks of cases, they do eliminate some problems associated with excessive headspace. Neck sizing can also prolong case life.
Sizing dies for the 308 Win will work to size 307 Win brass as the only difference is the fact that 307 Win is a rimmed cartridge.