I know this might cost you some shots, but it will help in the long run. I would take the dog with you in the blind and tell him to stay and hold him with you hand while you hunting partners shoot. If he tries to break, tell him NO and hold him steady. Then, when everybody is done shooting, say your fetch command (I use my dog's name) and let him go. After that, keep him in your blind and him to stay and this time you shoot, make sure he is in reach just in case he still tries to break. If he does, tell him NO. I do this in my training, but you said it didn't work, so try this out in the field. Good luck.