Does he mostly bite when you pick him up?
One of mine was really bad about that. I started to use a cage hook to pick her up and she quit striking and was OK to handle. I can pick her up barehanded now without a strike. She still gets hissy once in a while, but that I can live with.
Funny thing is, mostly she hisses when she's put down. It's hilarious--it's like she's doing "so there!" and a snake flounce.