I would have thought that bringing live ammunition onto a film set involving the use of prop guns would be absolutely forbidden (with the possible exception of security staff who might be armed in some locations for crew safety).Doesn’t matter if the script called for him to pull the trigger or not. There shouldn't have been live rounds on set, much less loaded into a gun, much less handed to an actor expecting a inert prop gun without telling him and sent out into a scene. Every gun on a set is to be handled by an assigned tech, repeatedly cleared, & checked in & out, to eliminate any possibility of it being anything other than a prop, not a loaded lethal weapon. It is a professional production set, not a backyard barbecue hootenanny. There is no skeet shooting with the prop guns between takes. There needs to be a suspension of the basic rules of gun operation on set, because a gun is on set for one reason, and that is to aim at other people and pretend to shoot them. That’s literally what Chekov’s Gun is referring to. Every production needs the actors to be able to reasonably expect that their props are harmless in order to do their job. There’s a whole set of protocols and dedicated people responsible for enforcing it.
What possessed any armorer to load a prop gun with live ammo whilst on set? The blank or dummy ammo that I've used in the past looks very different to live rounds (crimped ends, plastic/wood/wax projectiles, different colors etc.) and I can't see this being confused unless the person had zero experience with firearms.
Did someone just bring along their personal firearm and leave it loaded on a table? Or plan on doing some target practice later with a prop gun? Or was it a disgruntled employee (and there were some) who wanted to cause some damage to the production?