There's a theory going around Turnbull that the film was sabotaged and someone purposefully left live ammo in the gun to accomplish this. Also heard crew members were firing weapons on location so that could be where the live rounds came from.
There is usually people who bring their own firearms and ammo on set when they are out in the country or mountains, more common when it is westerns. There was a major break in protocol with the weapon when back in the day it was two people that checked to make sure there were no live rounds and other blanks, I believe it is now four people who are supposed to check the firearms, I believe that method came into play after Brandon Lee was killed on the set of The Crow.
Alex Baldwin has been coached on what to say. He should just say it was a terrible accident.
