It's difficult to find statistics on the number of celebratory gunfire incidents each year, but in this country it's not terribly common, said Katherine Terry, program administrator for UAB's Injury Control Research Center, which studies a wide range of health issues, such as injury prevention and safety.
"It's more common in Iraq," said Terry, noting that in the U.S. it's more common in the largest cities. "New York, New Orleans and Los Angeles have the biggest problems."
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The danger in a bullet is its speed and mass when it strikes, said Ken Howell, an Alabama native and nationally known firearms expert in Stevensville, Mont.
A common .22 caliber long rifle bullet fired from a pistol goes at about the speed of sound, Howell said, which is about 1,100 feet per second at sea level. From a rifle, such a bullet leaves the muzzle at about 1,260 feet per second.
Coming down, depending on wind resistance, angle and other factors, according to National Rifle Association data, the bullet is traveling between 300 feet per second and 500 feet per second, Terry said.
Since a bullet, even a small one like a .22, going 100 feet per second can pierce skin and one going 200 feet per second can shatter bone, a bullet coming down from a celebratory shot "can rip through lots of skin and bone. And if it hits your head, you're in lots and lots of trouble," Terry said.
The faster and bigger a bullet is, the more damage it can do. The angle at which it's fired is another factor, Howell said.
"One thing is, it's dangerous enough when it goes straight up and down. It's far more dangerous on an angle. The bullet goes faster," Howell said.