Well my special order Lee sizing dies have arrived. They are indeed "file hard". For my final size die for my for 308 jackets I ordered the die .302. After the initial bell on the mouth of the die, it measures .311, then within a half inch, it reduces down to .302. It appears that the die stays .302 for about another half inch before the die opens up again to relieve the pressure so it can be pushed through the die to remove it. As far as the amount of material in the die to insure durability, I predict these dies will produce very consistent results for years. As a matter of fact, I may need to shorten the .302 diameter section to use it for brass reduction. I will only be able to tell after I use it some. We shall see.
I will probably not have time to anneal some brass and size some brass for a little while, so I will update the thread when actually using the dies. My initial impression is that these will be excellent sizing dies for resizing brass cases and at $38, an even better value.