No bear shooting experience but have done alot of hiking in bear country over the years. You really have to piss of a black bear to get them to charge at you. Usually has to do with getting between a sow and her cubs. Most black bears want to avoid contact with people themselves including the ones that frequent high population areas.
That said if you were forced to shoot a bear with what you have (.40 or 00buck) I would aim for the head/face. If it didnt kill em it would likely change their ideas real quick. Just a thought.
With a black bear attack you respond the opposist from how you would with a grizzley. With a black bear you need to fight back with everything you have vs playing dead with a grizzley.
J-
edit: good thing that NJ banned/severly restricted bear hunting some time ago, looks like it is working out great
The population has been on a pretty steady increase and they are confirmed in every single county in the state.