The Importance of Rule 1
Sometimes the facts of a case are almost too painful to even think about. What kind of moron points a gun, even an unloaded one, at a child?
The girl's brothers told police that they had been cleaning their room when Eric Hummel came in with his 9 mm Glock model 17 and said things such as, "You should never mess with the gun," the affidavit states.
One brother said his father had pointed it at him two or three times and the gun made "a little pop sound," according to the affidavit. Eric Hummel pulled the top of the gun back once and had forgotten he "put the bullets back in" when he "shot our sister," a brother told police, according to the affidavit.
Evidently the gun had an empty chamber with a loaded magazine in it when it was being waved around and pointed at the boys; the perpetrator then racked a round into the chamber and had his finger on the trigger while pointing the gun toward his daughter when she walked into the room.
This presupposes a blatant violation of two vital safety rules: 1.) Always keep the gun pointed in a safe direction, and 2.) Always keep your finger off the trigger until you are ready to shoot.
Rule 2 is especially important when you are using a striker-fired pistol, such as a Glock; a violation of rule 2 can (and did in this case) turn deadly when coincident with a violation of rule 1.
I doubt that the perpetrator had ever taken a firearms safety course, because these safety rules are firmly fixed in every student that receives a course completion certificate from an NRA course.
Serving as a fail-safe, adherence to Rule 1 can keep even a negligent discharge from becoming deadly.
/fl