realy it is not unuseual to see bh shoot differant than fp...i shoot with field tips all summer and have to adjust in the fall for broad heads...one of the things i found that helps is tuneing your arrow also.i now align my fleching with my bh,,and my nock with the fletching and i spin test the bh to see is thier true...it dont take long and it helps.
anouther thing is if you shoot 3 vane arrows ,,shoot 3 blade heads...i know most of you already know this but it might help some. thanks