Something else just occurred to me. A semi-automatic or a fully-automatic weapon will not cycle with blanks. Some sort of blank adapter must be used to make them cycle. The military uses orange adapters that slip into the barrel and lock on the bayonet lug. Hollywood would have to use specially made barrels with a restriction on the inside. An any case, firing a live round while using one of those will cause some sort of amputation to be awarded to the shooter.
So, if Baldwin was even handed a weapon that could shoot a live round something is amiss. Maybe Hollywood uses editing trickery to make the weapons cycle.