I recently purchased a .257 Weatherby Mark V KCM rifle. I plan to try the Hornady 110 Gr EL-X in it as well. Is your rifle custom or factory? If it’s a factory Weatherby rifle, I recommend the COAL listed in the Hornady 10th Edition of 3.190.”(I haven’t found in any data source that gives a COAL specifically for the 110 Gr ELD-X yet). The reason for this is that Weatherby throats are long anyway. It is highly likely that if you try to seat your bullets close to the lands, your COAL will be too long to fit your magazine. If it is a custom rifle with a shorter throat, I would suggest seating your bullets .005”-.010” off the lands to start with. You might have to play with the seating depth to wring out maximum accuracy from your rifle. Obviously, you’ll want to make sure they fit your magazine as well. I hope this suggestion helps.