No way to do it legally.
If you are passing through either state, having it unloaded & locked up renders it legal under Federal law. Once you stop the car, even just to use the rest room, either state (especially NJ) might lock you up on felony charges. If you are going into the state, stopping to work, and then returning to Delaware, you would almost certainly be prosecuted if you were stopped.
Remember, also, that possession of hollow-point ammo is a separate crime in NJ...