Also the arrows are still spinning when they enter the target. Your target would have to be a PERFECT medium in order to stop the arrows the EXACT same way every time. Are all your arrows the same distance in the target every time, I don't mean close I mean the same, like down to a 16th of an inch. Probably not.

A cross wind could effect it as well. If one arrow had more of a cross wind during flight it might spin the fletchings faster than the others did. A head or tail wind would do the same thing, since it would simulate the arrow going faster or slower.

Paul