P.A.
both of my kids were head bangers, my daughter out grew it by the time she was 20 months, my son still does it- he'll be 3 in July. He doesn't physically hit his head with his hands, he uses the floor. No disabilities or anything like that, it's just what he does. He seems to do it less and less so I'm thinking it'll be soon when he quits. So far, the best thing I've found was to just ignore it. Anything else drew too much attention to the action and it would make it worse, i.e. he would hit his head harder or more often. Good luck to you.