With all due respect Yo-Yo, this is oversimplified thinking. Sometimes you cannot be sure of outcome of a given situation, particularly when you don't have all the facts of a situation.
With all due respect to you, Amendment10, I will allow you to construct any strawman argument you wish that would justify a warning shot. The military doesn't teach warning shots. The police doesn't teach warning shots. If the situation justifies discharging a weapon, you shoot to stop the threat. If it does not justify stopping the threat, then it does not justify discharging your weapon at all.