If it’s a real gun..as has now been reported.. Baldwin should have checked it out.
And if he was pointing a gun at,or towards someone in order to get a camera shot, there should not have been a live person behind the camera.
I am assuming part of the scene required him to squeeze the trigger.
Otherwise his finger should not have been on the trigger.
He was rehearsing a scene. Why would ANYONE need to pull the actual trigger in a rehearsal?