Reading the news today, I think there is more to this story. The unionised crew had walked out over poor working conditions, a few hours before, and the film company had brought in some non-unionised workers at short notice. I understand that live bullets are banned from all film sets to avoid inadvertent use. Also that if anyone is pointing a prop gun directly at a camera then there should have been lots of safeguards, including a perspex screen between gun and camera. It would appear none of this was in place. I think there is more to come out.