I do not think it is abnormal to answer your door with gun nearby at odd hours of the day.
According to all the reports I read, the cops arrived at 5:17 AM to serve Willis who opened the door with a gun in his hand. OK, so far no harm no foul. Then a cop gave him the papers and Willis put his gun down to read the papers. Then he apparently got upset and picked the gun back up. Big mistake, dude. And then opened the door, walked outside and fired a shot which was returned by one or both of the cops and Willis was fatally struck. According to reports, the deceased was “having problems with alcoholism”. As Tonto always said, “Firewater and firesticks are bad match, Kemosabe.”