True. That was a MSM story. Good catch. From what I have been reading, it was a real .44 single action revolver (similar to the ones in the 1800's) that was supposed to be loaded with blanks. Obviously the chain of custody on the set was inadequate. It wasn't the gun it was (as always) the humans handling the gun. I don't think it was truly a 'prop gun' because those are a specialty item that cannot take live rounds.
IMO, a real gun was used for authenticity (supposedly loaded with blanks) and I'd bet they were trying to get a 'muzzle flash' shot with Baldwin's mug behind the gun which would have put the cinematographer in direct line of the shot. The director would have been right behind the camera checking out the shot. The .44 slug went straight through the cinematographer and into the director. He survived because the kinetic energy of the shot was greatly weakened after going thorough the first body.