I remember back in the late 70s a female SP at the Peterson AFB gate was playing with her gun while her boyfriend watched and shot herself in the leg.
She claimed an armed intruder did it and the base was under lockdown for several hours. Later the truth was found, and she was discharged for the discharge.
There was an incident at Eglin when the Army were down for joint exercise and they were performing the gate duties. One of their soldiers drew their weapon and it went off. Needless to say they were not allowed to carry a loaded weapon for the duration.