Beating target panic while using an index finger triggered release is not an easy thing to do.For me I went pure back tension for two years and now use a pinky triggered release.
I beleive the primary elements in beating it are to be relaxed and not to care so much.Focus on repetition or sequence of form and if you break any of that sequence let down.The best target archers let down almost 1 out of every 3 shots.To be relaxed when making the decision to complete the shot sequence or not will set you free! Good luck!!