In the wake of the tragic accidental death of the cinematographer Halyna Hutchins from a misfired weapon on the New Mexico set of the movie Rust, the role of stunt firearms in film, and the props departments who manage a maze of safety protocols, are under scrutiny.

Hutchins, 42, died and director Joel Souza was hospitalized after a prop firearm was discharged by the star and producer Alec Baldwin. While the exact chain of events that led to Halyna’s death are unknown – the police are investigating – they appear far out of line with a profession seemingly protected by safety nets and could hasten a shift away from staged blank rounds to digital effects.

Fatal accidents on film sets are exceedingly rare – there hasn’t been an accidental shooting death since Brandon Lee was shot at close range by actor Michael Massee on the set of The Crow in 1993. Film and TV crews generally use firearms loaded with dummy rounds, which look like real bullets but are completely inert, ie they contain no propellant. An insufficient check would mean live ammunition or blank cartridges (rounds with no projectiles) that still contain powder charge and primer, could remain in the gun’s barrel.

On film and television sets, prop weapons fall under the the purview of the art department, and in particular, the property (props) master. Props masters and their assistants handle, clean, monitor and inspect the stunt weapons on set, which resemble real guns but are not the same. “We never use real guns under any circumstances at all,” said a props master who works in TV and spoke to the Guardian on condition of anonymity. “That said, in almost all cases, prop guns are smithed from real guns. Blank firing weapons are modified to fire safely and under strict protocol. When done properly this process is truly very safe.”

Even pellet guns are governed by strict protocols – checked not only by the prop department but the assistant directors and any actor handling it. “There’s a whole chain and process and protocol, it sounds like was not followed or not followed properly,” said the props master regarding the Rust accident.

That protocol includes checks of the prop guns before and after use, and a review of the choreography and props with all participants. After a take, the assistant director along with the props master has to re-verify that the magazine is empty and removed. Props masters also check the barrel after every take and clean out dust and debris – a blank could fire even a pebble like a projectile. “There’s just a number of checks and balances to prevent any errors from happening,” said Nathan Alexander, an assistant props master on films such as Avengers: Endgame.

“When they roll, you’re listening, you count how many times they fire, and then you go in and take the gun away from the actor, check it and clear it after every single take,” said the anonymous props master.

According to an email by a local film workers union chapter, IATSE Local 44, the prop gun that killed Hutchins contained a “live single round”. New Mexico crew members, including the props department, were not members of the union, which negotiates safety protocols on film sets. Santa Fe police are still investigating the incident and have not confirmed the union’s description of events, which were first reported by Variety.

If true, the presence of a live round — as in, a round with a projectile (bullet) — would be a rare violation of basic safety standard. “Never, never, never should a projectile ever make it on to a movie set,” said Alexander.

For larger or more complicated weapons – long guns, automatics – studios and props departments are required by law to retain a firearms specialist known as an armorer. In recent years, studios have moved toward retaining at least one armorer for any scene involving a prop firearm, to protect from liability. “As a culture, it’s preferred to bring in an armorer any time a gun fires,” said the props master.

Even with all experts on set adhering to all protocols, performers still need to follow the script. The anonymous props master recalled an incident with a popular actor who fired only two blank rounds when he was scripted for three. When the props department went to take the gun back “he shot the gun down into the ground, which is essentially safe – no one got hurt, and no one would get hurt – but he fired it unknowingly and everyone freaked out, and they turned to look at us”.

The risks and onerous responsibilities of prop firearms have led some productions to scrap such scenes entirely in favor of digital editing. On Friday afternoon, Alexi Hawley, creator of ABC’s cop drama The Rookie, said in a staff memo obtained by The Hollywood Reporter that “live” weapons – props with the capability of firing projectiles – would no longer be used on set. Going forward, the police procedural will use Airsoft guns, which fire pellets instead of bullets, with computer-generated muzzle flashes added in post.

The props master told the Guardian that his current production, a TV series, decided to scrap plans for a shootout scene in the wake of the Rust accident. “They had taken all possible precautions, they’re a very responsible production and they had not one armorer but two to handle all of these potentially chaotic things,” he said, but the production ruled out blanks in favor of digital effects for the rest of the show.

“It’s such a burden. The protocol is going to become even stricter, rightly so, and safer. So why would you not do it all digitally?” he said.

“The protocols make this highly technical work safe and reasonable,” he later added over email. The death of a crew member was “totally preventable and shocking. I truly believe that scenes like this can be done safely, and are done safely, all over the world, all the time, every day.”