If you are shooting a 2 cam, it could be a problem with cam synch. If a 1 cam, it could be a nock travel problem. The nock point could be set too high, and the top of the arrow may be pushing off the top of the hole in the Biscuit, giving you a low tear by reaction to that. It could also be a problem with arrow spine. It could be too much heel of the hand in the grip also. It is kinda hard to tell without more info.