Live ammo in a prop gun sounds like a plot device in a cheap detective series. Didn’t I see this in an episode of Columbo or Perry Mason?
The Perry Mason episode had a prop manager Jackie Coogan (Uncle Fester)put a gun with real ammo in an ammo box along with 5 other prop guns.
Conversely, the actor abuses everyone on set, including the prop people, who set him up for killing someone during filming. Another interesting plot twist! This guy is hateful and treats people miserably, so you could see that being done to him.