The fundamental rule of firearms safety is normally that the person firing a gun must inspect it before using it. But this was a prop gun. The armorer is supposed to load it carefully with a blank, and no one else is supposed to touch it (except maybe the prop master) until the actor fires it. The last thing they want is for the actor to try to inspect the prop gun, poking inside the barrel and the chamber or taking out the blank, inspecting it, and replacing it, since he is likely to mess up what the armorer did with the blank and thereby possibly cause a dangerous misfire. Preparing and inspecting a prop gun should be left to professionals, and actors should leave the props alone. The assistant director had no business handling the gun at all. It should have been the prop master who gave it to Baldwin. My question is - why was any live ammunition on the set in the first place?