"Prop guns" that go bang on a set are almost always real guns, some may be modified. Purpose-made for make-believe would be a small minority. The Prop Master is not in charge of them. They have stunt coordinators, fight scene coordinators, and a separate person in charge of all things related to the guns.
Checklists and protocols are strictly followed. Live ammunition should be nowhere near these guns, ever. I'm aware of an instance (my daughter does theater and cinema production) where re-loading of blanks was done to spec, and as per usual everything was inventoried before and after. After reloading blanks the inventory exposed that ONE primer was missing. All cartridges were disassembled and the missing primer was found INSIDE one of the cartridges. That primer could have been a projectile capable of killing someone. Strict disciplinary action was taken. That's my guess on what COULD have happened here.
It would be unusual that the angle of fire would not be strictly controlled also. In Westerns and any production involving combatants in dirt and such, debris can and will get in barrels and I know of an instance where an actor was injured by debris (probably sand) from over forty feet away. It was an arm abrasion that resulted in a (probably unnecessary) ER visit. "Abundance of caution" and such. The shooter had plenty of excuses (injured party missed a cue, was in the wrong spot, all true), but again, strict disciplinary action was taken against the person who pulled the trigger.
Baldwin could have been in a scene that called for firing directly at the camera I suppose, but there would have been some sort of polycarbonate barrier with a hole(s) for the camera(s) and lead production mucky-mucks wouldn't likely be behind it.
Honestly the more I think about it something sounds fishy. I feel very bad for all involved. Baldwin IS a smug hotheaded jerk, but dang. Something's weird.