OK, I'll add my 2 cents worth. I just grabbed a handful of my sized 9mm brass and ran some pin gauges in them. I'm using the U-die. The ranged from .346" to .348" ID varying by headstamp.
I think whoever it was that cautioned about the powder funnel expanding the brass is correct.
I turn my powder funnels on a lathe to make sure they're not affecting the neck tension.
Just measured my funnel with a micrometer and came up with .343", so you can see it's not expanding my brass. Now, the brass looks a little bulged when loaded (like the snake that just ate a mouse), but no creep to speak of, since it's really grabbing the bullet. After a match, I measure the overall length of the rounds that are left in full-moon clips and reseat the ones that are .005" longer than I loaded them. There aren't many, maybe 3 to 5 per 100 fired. But definitely none that are anywhere close to disassembling themselves in the gun.