A 9 millimeter bullet fired from a handgun weighs, on average 120 grams, and comes out of the gun with an average muzzle velocity of 1250 feet per second.This translates to 852 Miles per Hour. 1.5 times faster than an Airbus A321. Upon impact with a person, a bullet can tear straight though any tissue and fracture bone. This causes major internal damage and bleeding. If the person is not in the immediate vicinity of medical attention they will die.
A gun does none of this. A gun is only the medium in which the bullet can reach its potential.