A big part of the increase in "ghost guns" is that New York's definition of "ghost gun" includes not only the scratch made guns that most people think of as "ghost guns" but also any gun without an easily read serial number. So regular guns with obliterated serial numbers count as "ghost guns" in New York.

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.