Guns don't shoot balls. People shoot balls.

How not to do armed robbery:

A man comes into a convenience store, threatens the clerk with a gun, demands money, gets the money, demands cigarettes, puts the gun into his pants, pulls the trigger.

The man takes the money and runs, the clerk reports armed robbery by a man who shot himself in the balls, the man calls an ambulance about the balls, the ambulance and the police arrive.

The article does not say whether or not the injury was severe enough to improve the local gene pool.