Well it depends. Typically, arrows that are too weak of spine for the bow used will do this. Or your arrows are too long/broad head too heavy, etc, which would make them too weak of spine as well. Arrows that are too strong of spine will stay stiff, like big darts. But they will not go where you point them. If your handle is very big, then you will need weaker spine arrows to paradox around the large handle and go where you point them, and I think sometimes an arrow of the correct spine for the bow with the fat handle will fish tail a bit. I think anyway. That is according to my meager understanding. I just recently made my first spine tester, and am only recently making better matched arrows for my bows.