The legal blame lies on the whole production overall due to the gun safety standards on a set, but in all reality, the blame truly does lie on Baldwin. He was holding the weapon, didn't check it himself, and fired it at a camera with people behind it. I don't say this to deride Baldwin or anything, it's just simple gun safety facts and if this was anything other than a Hollywood set, there would be charges filed against Baldwin.
In my unqualified opinion, I wouldn't default to blaming the actor.
I don't know if the actor is expected to be qualified in handing firearms, or needs to have a firearms licence (I don't know USA gun laws).
In NZ I can not own a gun without a firearms license, but I can use one, under the supervision of the person who is responsible for the gun. That person would have a firearms license, would have undergone training and would ensure I have the knowledge I need to have and that I practice safety first. They would be there with me, watching, observing and giving instruction if need be. They would ensure the gun is in a safe condition and that the correct ammunition is in the gun. That I am in the correct place before I am handling the gun and that I am pointing it in the right direction and that safety is adhered to.
As long as I am not being an idiot, as long as I am following instructions then I would assume most culpability would be on the person in charge of the gun, not me.
In a business, like a movie making business there would also probably be culpability on the company to have policies in place, to hire the right people and to take action to ensure a safe workplace.
I don't know where the failings were in this specific case, and I am following, and will find out when these are disclosed.
It is very unfortunate for all, for the immediate victim, for their family and loved ones, for the actor who squeezed the trigger, for the director, for the props person, for the person in charge of the gun, for the producers of the movie, for everyone involved. This appears to be an unintended incident. Sad situation all around.