Neck sizing with full length dies

[Jack]

I would agree with Ol Joe- an intermediate step would be a good idea...like a 270 or 280 die, first, then neck down to 25-06.
I also agree it probably isn't worth it, unless someone gave you a tub full of free 30-06 brass.
And, you may have to neck turn the 30-06 cases after you neck them down to 25. Depends on the neck thickness of the original 30-06 cases, and the neck diameter of your 25-06 chamber.