Calvin,
Use your chronograph with "standard" data.
Hodgdon's .257 Weatherby data lists 78.0 grains of H1000 as maximum with Speer 100-grain boattails, for 3575. I worked up to 3550 fps with 100-grain E-Tips in my rifle, but the charge was only 76.0 grains. Accuracy and brass life are excellent.
