How can a BH shoot differently than a field tip when the arrow is leaving the bow straight?
Because an arrow NEVER leaves a bow straight...........It is flexing like mamba dancer.
That flex can and will cause the broadheads to catch wind and skid. This may only happen as soon as it leaves the bow but it will be enough to cause a slightly different impact point than field points.
It just seems to me that if you line up your knocking pt and rest, then your bow should be tuned
What a bow is at rest in not what that bow is at full draw and is not what that bow is during the dynamic of the shot. The cable rod side pressure will alter dynamic center point from static center point.Your grip can also do the same. Many forces working in a split second that cannot be accounted for when the bow is sitting in a vise