That might be a possibility... I remember Bourbonnais (the Vietnam Vet) had told Assam to “take a head shot” and she said, “No, I think he’s dead”. Perhaps, after Bourbonnais cleared the gun he decided to take the head shot himself just to be “sure” he was dead??? I don’t want to speculate much further than that, and it is speculation because no-one mentioned Bourbounnais firing any shots — although he asked the “paralyzed” male security guard to give him his weapon...
This is the only explanation, IMO, that would make sense. Someone mentioned that an inexperienced person clearing the chamber of the gun might say it was “jammed”. However, Bourbonnais doesn’t sound to me like someone who is inexperienced enough to mistake a “jammed gun” like that.
Obviously, the ammo found inside Murray’s body matched ammo found inside the Arvada victims and/or the New Life victims.