My broadheads are 4 blade Muzzy 100. Vented and not very large, but I too suspect planing is the problem.

However, I expected planing to cause vertical change in POI. How can it deflect the arrows horizonaly? and by that much? (7" at 20 yards). Did anyone encounter such?

My main concerned is not sighting in, but that this behaviour indicates something is wrong with the CB.