A receptionist for a psychiatrist would never just hang up on a patient that is clearly in distress the way the unsub was. Psychiatrists are always reachable on their cell phones for emergencies; if a patient is threatening suicide, to harm others or is clearly in the midst of a psychotic break. In fact, there are laws that require a psychiatrist to immediately see or at least talk to a patient in a mental health crisis.
The medical examiner refers to a recovered cartridge as a "thirty ought six Winchester". There is no such cartridge. It is possible he meant either ".30-06 Springfield" or ".308 Winchester".