Ive found that the CE estimator for what spine to use is too stiff for the guys that I assist and myself. CE says I should be using a 350 spine. I am a real stickler for these things. 350 was not the answer as the CE charts would lead a guy to think. Im getting great tears, and great broadhead flightwith fixed blades heads from point blank to 50 yards with 150's Mazima BLU RZ. If you were to believe the charts there is no way I should be able to do that. Broadhead tuning is where its at. Field points are too forgiving. Most guys have problems with broadhead flight because of too stiff an arrow so they think the charts are correct and they switch to mech or tiny heads to correct what is a spine issue.