You're not supposed to ever point a set gun at anyone
Really? On a movie set filming shoot outs? You've never seen a gun (hopefully a prop) pointed at someone in a movie scene? Ever? In your entire life? Really?
Do I really have to go dig up the infinite number of movie clips? Prop guns get pointed at people all the time on movie sets. It doesn't seem unreasonable to me that an actor not familiar with real guns would assume that professional armorers would be using prop guns. I'm sure Baldwin would not know the difference.
Alec Baldwin ain't heavy, and he sure ain't my brother, but I find your reaction disingenuous. IF you just said I hate Baldwin and hope he is screwed, then I'd be fine with that. But I find your faux outrage amusing.
I suspect if this had happened on a Chuck Norris set you'd have a different reaction. You will of course deny that, but I will doubt your sincerity.
This happened before the scene began filming, but then it just would have been an actor shot instead of a cinemaphotographer.