The latest Handloader's Journal has a great article on 257 Weatherby. They were using the Remington 700 in 257 Weatherby. Part of the accuracy problem with Weatherby's, even in a Rem 700, is the long lead for the bullet to jump to get to the rifling. Even with the 120gr bullets, they could not touch the lands and have the bullet seated in the case. Try to stretch your COL out to help with accuracy.