RE: new arrows shoot much diffently
Difference in spine between manufacturer's. I have some Carbon Hunter Express that shoot 1 inch high at 20 and my new GoldTip Pro Hunters shoot low and to the right about two inches in both directions. The gold tips are 5 grains heavier.
My original arrows are 350 grains
New arrows 355 grains but have a vane wrap on the back of the arrow.
Old arrows shoot a 4" Duravane, New ones shoot a 2" Blazer.