The bullet fired into the air will return to earth at terminal velocity, usually falling back at speeds much lower than those at which they leave the barrel of a firearm. Nevertheless, people can be injured, sometimes fatally, when bullets discharged into the air fall back down. The mortality rate among those struck by falling bullets is about 32%, compared with about 2% to 6% normally associated with gunshot wounds. The higher mortality is related to the higher incidence of head wounds from falling bullets.
A study by the U.S. Centers for Disease Control and Prevention (CDC) found that 80% of celebratory gunfire-related injuries are to the head, feet, and shoulders. In the U.S. Commonwealth of Puerto Rico, about two people die and about 25 more are injured each year from celebratory gunfire on New Year's Eve, the CDC says. Between the years 1985 and 1992, doctors at the King/Drew Medical Center in Los Angeles, California, treated some 118 people for random falling-bullet injuries. Thirty-eight of them died. Kuwaitis celebrating in 1991 at the end of the Gulf War by firing weapons into the air caused 20 deaths from falling bullets.
Firearms expert Julian Hatcher studied falling bullets and found that .30 caliber rounds reach terminal velocities of 300 feet per second (90 m/s) and larger .50 caliber bullets have a terminal velocity of 500 feet per second (150 m/s). A bullet traveling at only 150 feet per second (46 m/s) to 170 feet per second (52 m/s) can penetrate human skin, and at 200 feet per second (60 m/s) it can penetrate the skull. A bullet that does not penetrate the skull may still result in an intracranial injury. So, don't fire that gun. What goes up must come down, and there is a chance it will come down on a head!
Yes. For instance, some terrorists had gatherings where they basically fired guns in the air and stuff, and some of them were actually killed from the bullets when they came back. I thought that was pretty hilarious. So, yeah, they do have the potential of injuring/killing people.
Well, what goes up must come down (not the price of gas but that's the answer to another question) and that bullet has to come down somewhere. I would think it would fall at a lesser speed that when it left the gun however. I know an arrow sure does come back down and you do not want to be around when it does...would think same would apply to a bullet.
Yes they cause grievous injury to innocent people. In India at the marriage ceremony some people fire upwards from their firearms which many timed hit some person and the bullet causes fetal injury and sometimes death. People think it to be symbol of status but it is very dangerous and may land you too in trouble.