I use 264 Win mag brass for my 257 Weatherby. The only problem is, fire forming the cases sure wears out the barrel faster. It would be nice to have two rifles, one to fire form with, and the other to do the hunting, or target shooting only. It may be worth it in the long run to just buy the expensive Weatherby brass.
I like the idea of the 145gr 25 caliber bullet for the Weatherby too.
The H1000 is the powder that I use with the 110gr Accubond @ 72.0 grains. It shoots very good there for me. Chrony'd them right at 3400 fps. My group at 100yds is .777" which works for me.