the bullet is easily identifiable and should have been “seen” as a potential “live round” pointy or not.
What’s in the chamber? Simple question. Simple answer.
No one cleared the chamber or confirmed what was loaded was correct before the shoot.
I understand that as an NRA Certified pistol instructor, IPSC action shooter and I reload my own pistol and shotgun ammunition.
Sometimes the questions can be too simple. How about, "What's in the barrel?"
Prior use of the firearm may have allowed a bullet to be lodged in the barrel. A blank round can propel such a bullet as if it had been fired from a live cartridge. Perhaps there was no "live round" in the gun.
The check that the armorer did and the AD did to verify a "cold gun" was inadequate. I could believe that they also failed to check that the barrel was clear. Perhaps it was a bullet lodged in the barrel along with a mistakenly loaded blank that caused the death.
Many unfortunate incidents end up being caused by a chain of actions, none of which alone could cause the damage inflicted.