Bullets fired into the air usually fall back with terminal velocities much lower than their muzzle velocity when they leave the barrel of a firearm. Nevertheless, people can be injured, sometimes fatally, when bullets discharged into the air fall back down to the ground. Bullets fired at angles less than vertical are more dangerous, as the bullet maintains its angular ballistic trajectory, is far less likely to engage in tumbling motion, and so travels at speeds much higher than a bullet in free fall.
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 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.
Firearms expert Julian Hatcher studied falling bullets in the 1920s and calculated that .30 caliber rounds reach terminal velocities of 90 m/s (300 feet per second or 204 miles per hour). A bullet traveling at only 61 m/s (200 feet per second) to 100 m/s (330 feet per second) can penetrate human skin.
In 2005, the International Action Network on Small Arms (IANSA) ran education campaigns on the dangers of celebratory gunfire in Serbia and Montenegro. In Serbia, the campaign slogan was "every bullet that is fired up, must come down."
Bullets often lodge in roofs, causing minor damage that requires repair in most cases. Normally, the bullet will penetrate the roof surface through to the roof deck, leaving a hole where water may run into the building and cause a leak.[1