Re: .257 Weatherby Magnum - Bullet selection
I know of 6 257 Weatherby's and all of them shoot the 100g Nosler BT, and none of them have experienced bullet failures. In otherwords, what they shot was laying right where it was standing when it was hit.
I also have shot a coyote at 50-65 yards straight away running shot and the bullet hit the yote in the butt and came out it's chest.
The 100g Ballistic tip is not a varmint bullet.
I think that you will do just fine with the 115 CT, part of the fun is trying and seeing what happens!