We are over thinking this some. First , good shot placement. Always does not happen. A 165, a 150, a 180. a 130 well constructed bullet will do better then the NBT's if the shot is a little off. 25-06. 257, 243 are awesome antelope guns. Just choose a good bullet. I have had less damage with a shoulder shot with a good well constructed bullet as a buddy decided to use a NBT in 257 weatherby and shoot and basically had an un edible goat. No need to switch grain bullets unless they are the nbt. If you think this is just all BS , keep shooting the NBT and you will find out the hard way. Shot placement is # 1 priority though.