RE: MULE DEER RIFLE CHOICE!!!
Out of those 2 Id go with the 257Weatherby. It is one of the flattest shootingcalibers there are. The 25cal bullets have some of the best B.C's.out there. Out of those bullet choices I would go with the Nos Part. If you hand load you can get those 100grns upto 3650-3700fps now your talking.
The only draw back is the ammo costs more. If you hand load then that 257 can be a monster. If you dont handload then they are alot closer in performance. Those 150grains in the 7mm at about 2800-2900fps wont be that flat though.
If you havent purchased the gun yet a 7mm STW maybe something to check out also.