Hi, I am Dr.Bruno. I have read your question and understand your concerns. Let me try to help you Question 1 : If someone has a complete abrupt transection of the spinal cords by a gun shot through the mouth would this cause complete paralysis immediately? Answer 1 : Yes. If the bullet passes through spinal cord, there will be complete paralysis immediately. But if the bullet passes through carotid vessels, there will be a few minutes before paralysis Question 2 : How would the arms fall if they are holding a gun? Answer 2 : It depends on how the bullet went through Question 3 : How long would the heart beat in bradycardia after the injury? Question 3 : 5 to 10 minutes usually. Again this varies depending on the structures which have been injured by the bullet Hope you found the answer helpful. If you need any clarification / have doubts / have additional questions / have follow up questions, then please do not hesitate in asking again. I will be happy to answer your questions. Let me know if I can assist you further. Take care.