That' s a shame to have a perfectly good shoot spoiled by someone with poor manners or self control. Normally if their temper gets them that bad, they don' t have a chance to win anyway. I would probably look for a way to break the tension for the group, humor or assistance possibly. I would also try to give special attention to the youth shooter to make sure he or she did not go home thinking that behavior was normal. Keeping your own head in the game would be a challenge. Recognise his " head games" for what they are, and don' t let him change your game plan. Focus on your approach to each target and your shot sequence. Also know that he is spending way too much time with temper tantrums and mental games to ever be a threat to you as a competitor.