Last night, I was trying to help a friend bare shaft his bow and ran into an odd scenario that I can not explain. He is shooting off the shelf with a Big Jim Desert Bighorn 56" 58 lbs at 28" draw. His arrow is a carbon express 350 11.45 gpi cut at 30" long. He has 300 grains up front. We are seeing a constant nock right flight. We did confirm with a scale that his bow is pulling 58 lbs at 28". Here is the question. He is under the impression that a nock right flight is always an over spined arrow for a right hand shooter. Is that correct? I can not believe that arrow is over spined with that amount of weight up front. I watched him shoot and I do not see him torquing his bow at all. The other hypothesis we came up with was the arrow is under spined and could be slapping the riser causing the same end result. We could not see the arrow slap the riser or hear and slap at the shot. We can not find any marks on the arrow or the riser to support the idea either. What else could be causing the issue if the arrow is not over spined?