I shot Beman MFX Classic 400 with 225 grs. upfront(100 gr. insert with 125 gr. point),flew like darts.I shot them out of a 64",Death Adder 55#@26(about 61#@28).A Blackhawk Vapor 3000 has a spine of .400,same spine as the Beman 400.I have had bows that I changed point weight 50 grs. and they was no difference in where they were hitting.On bows cut past center they are not as critcal to a 50 gr. change then bows not cut to center with carbon arrows.This has been my experience with carbon arrows.