It’s relatively small, but it leaves the muzzle at three times the speed of a handgun bullet. It has so much energy that it can disintegrate three inches of leg bone. “It would just turn it to dust,” says Donald Jenkins, a trauma surgeon at University of Texas Health Science Center at San Antonio. If it hits the liver, “the liver looks like a jello mold that’s been dropped on the floor.” And the exit wound can be a nasty, jagged hole the size of an orange.
These high-velocity bullets can damage flesh inches away from their path, either because they fragment or because they cause something called cavitation. When you trail your fingers through water, the water ripples and curls. When a high-velocity bullet pierces the body, human tissues ripples as well---but much more violently. The bullet from an AR-15 might miss the femoral artery in the leg, but cavitation may burst the artery anyway, causing death by blood loss. A swath of stretched and torn tissue around the wound may die. That’s why, says Rhee, a handgun wound might require only one surgery but an AR-15 bullet wound might require three to ten.
