I have forgotten the details but I think it was Jon-Erik Hexum who died in a similar manner. (As mentioned a couple of years ago on this GetBig Board.)
I've been around firearms all my adult life and find it strange that any lethal weapon could be found on a movie or TV set.
Prop 'masters' in my time ensured that any prop used in a scene was a safe prop that could not cause harm and I am sure that he or someo other responsible individual on the set would have enough common sense to insure that a prop pistol was not harmful in any respect even though it wasn't a 'real' firearm.
Someone on that set fooked-up entirely!
Stunt, that was the whole problem: they weren't using standard blank rounds and "dummies," but MAKING THEIR OWN by modifying factory ammo!
Each bullet was disassembled.
For dummies, the powder was emptied. The shell was placed in the gun's cylinder and fired to detonate the primer. The lead tip was then reinserted into the casing, leaving a dummy round that looked like an ordinary bullet, but could not be fired.
Blanks were made by removing the lead tip, emptying only a portion of the propellant powder, and then replacing the tip with harmless cardboard wadding. This created a bullet that would produce the sound of a fired round without projecting anything dangerous.
What investigators believe happened is that the prop-master failed to detonate the primer in the dummy that was used for a close up shot. Several cast/crew members reported hearing a "pop" when the trigger was pulled during that scene.
They suspect the sound was the primer firing, which they speculate was enough force to separate the tip from the casing, and lodge it in the barrel of the gun.
Then, when a blank round was inserted into the gun and fired, the charge was enough to dislodge the dummy tip from the barrel and project it like a normal bullet would travel.
I have no idea how probable this all is, but that is what the forensics report offered.
Regardless, there should NEVER be live ammo on a set, and the gun - real or prop - should have been inspected before the scene.