I use a head halter. You might want to try putting him on him and let him wear it around the house. When a puppy is young his mother will "bite" on his muzzle to tell him he was bad. Also, a mother dog picks her babies up by the back of the neck making them go still and be caml. This combination will signal to your dog to be calm and it might even help with his agression (recomnded by my trainer)

I use the head haltie, but not to train. I do use it to train not to pull. Other whys I don't use it at all.

Ash