Loading for a 270WSM as well as a 300 Win Mag. My velocity spread from high to low average about 50-60 FPS. I am using CCI bench rest primers, uniforming the primer pockets and trim all to same length. The cases are also wieghed. A friend of mine told me that I should switch to a magnum primer and this would help me to obtain a more uniformed spread of velocity. If I switch do I need to cut back a powder charge?