The least charge than could be brought is manslaughter, by reckless handling of a weapon. “Shoulda, coulda, woulda” does not mitigate the chain of events in the least.
Waving a pistol, or in this instance a revolver, like some kid with a cap pistol, in an obvious bit of horseplay, displays an egregious lack of discipline and maturity.
Alec Baldwin is not known for maintaining honesty, maturity, or self-discipline. Karma is such a b!+c# kitty.
That doesn’t sound like a gun that can be fired “accidentally”.
Too many manual steps.