Again, because either your bow, the arrow, your grip, or one of or all of the above is out of tune..If a fixed balde broadhead of the same weight as your practice field points don't impact very nearly the same, then something is out of whack and by simply switching to a mech. head is only putting a bandaid on a problem, not to mention the fact that is your arrow aren't flying true, they also will not penetrate as well as an arrow flying true..you guys need to learn how to find and fix the problem instead of taking the easy way out..