I like my 416WBY, but I converted my Ruger Magnum bolt gun in 416 Rigby.
My Grandfather's fav is the 300WBY, he's had it forever and pounded tons of Moose with it many a year.
Problem is, guys adjust the die down on the shellholder and get to loading, paying no attention to how far they're pushing the shoulder back, which is TOO FAR to keep the shoulder snug against the chamber and the case well aligned with the bore... improper die adjustment IMO.
Black Hills and Midsouth Shooters Supply has Federal brass for the Ultra, I'm told, which shouldn't be a soft as Remington stuff.
Federal case weights are all over the place, remington's a bit better. I did measure the Remington stuff I had from three seperate lots of factory ammo. A 4 grain spread in case weight proved to only be less than two tenths of a grain spread in actual case capacity when weighed with water though, and that was checking all 60 cases. It don't get better than that.
Once you overload a belted case and it gets sticky over the belt, which they will, you can't size it down with a FL die like you can this same pressure expansion ring area on a non-belted case, simply an inferior design from a reloaders standpoint.
I'm not ready to get rid of my WBY chamber but, I do keep the pressure down below what expands the belt after the initial fire forming. If I could, I'd but Lapua brass for any belted case I could.