Load Bullets Release For Free

Upon being struck by the gun's firing pin, the percussion cap detonates and ignites the propellant; the resulting rapid expansion of gases in the gun's closed firing chamber propels the bullet forward at high velocity down the bore. The cartridge case is left in the chamber and must be ejected by mechanical means.

At some point high in the air (work it out yourself) the bullet will stop and begin falling. It would reach its terminal velocity of about 30 mph quite quickly and will fall back to earth.

As the propellant chemicals burn, they generate lots of gas very quickly. The sudden, high pressure of the gas splits the bullet from the end of the cartridge, forcing it down the gun barrel at extremely high speed (300 m/s or 1000 ft/s is typical in a handgun).

Hitting Other Objects For example, if you drop your cartridge near a steel object and it lands at the perfect angle with enough force, the bullet could go off. When there's enough force, the impact on the primer would mimic the impact of a firing pin after the trigger of a gun is pulled.

As already noted in other answers: No rounds will "fire" unless the spark is created inside the metal cartridge of ammunition, and possibly not even then. When a round "fires" in the magazine, the bullet will separate from the cartridge, but not with much energy.

First, always treat a firearm as if it's loaded, and point the muzzle in a safe direction. If the firearm has a safety, put it in the safe position.

A bullet with sufficient energy will have a cavitation effect in addition to the penetrating track injury. As the bullet passes through the tissue, initially crushing then lacerating, the space left forms a cavity; this is called the permanent cavity.