Baldwin’s culpability as an actor lies in how he accepted the gun from the assistant director instead of the armorer and accepted the gun without being present to observe a safety check, something which he should know not to do since he supposedly had the mandatory safety training. The assistant director is not the armorer and is unqualified to declare a gun ”safe/cold". When guns are handed out prior to filming a scene at least 3 parties are supposed to be present to observe a safety check conducted by the armorer. These are the actor, armorer, and the director/an assistant director. The armorer is the qualified expert. The actor should want to know that they’re not about to shoot someone with a real gun and real bullets. And the director/assistant director acts as a representative of the downrange cast and crew. This is supposed to be done every time a gun changes hands on set.
Sadly, the most interesting thing I’ve ever witnessed at my local FFL was a lady coming in to pick up a $10,000 custom over under shotgun that got shipped in from one of those old-world heritage custom shops as a gift for her teenage daughter.