Alec Baldwin's Rust crew accused of breaking at least THREE movie industry gun ...

The fatal shooting by Alec Baldwin of a cinematographer on the set of Rust could have been avoided if Hollywood guidelines regulating the use of weapons were followed, according to documents.

Baldwin appears to have violated rules against pointing a gun at a member of the cast or crew unless absolutely necessary. Firearms are also never to be left unattended and blanks are never to be used, guidelines state.

Any weapons on set are also never to be used for 'horseplay.' According to reports, the gun the 63-year-old actor used to accidentally kill Halyna Hutchins was used by crew members to shoot at beer cans just hours before the incident. 

The International Alliance of Theatrical Stage Employees, the union representing workers on sets of films and television shows, issued an industry-wide set of safety standards and rules governing the use of guns.

'BLANKS CAN KILL. TREAT ALL FIREARMS AS THOUGH THEY ARE LOADED. "LIVE AMMUNITION" IS NEVER TO BE USED NOR BROUGHT ONTO ANY STUDIO LOT OR STAGE,' according to the guidelines, which were obtained by Fox Digital.

In the days before the tragedy, IATSE had been threatening a large-scale strike that would have crippled Hollywood production. 

Among the complaints were overworking staff and poor rates. 

Baldwin recorded a video of himself encouraging the union members to strike if they felt they needed to, saying studio bosses ‘don’t give a f**k about you’, that the union shared online. 

Guns should also never be pointed at anyone ‘unless absolutely necessary to do so on camera,’ according to the guidance.

Those on the set must also never engage in any ‘horseplay’ with the firearm.

Santa Fe Sheriff Adam Mendoza told reporters last week that a live bullet was loaded into the revolver used by Baldwin during rehearsals for the Western on October 21.

Baldwin held the gun when it discharged, firing a bullet that killed Hutchins and wounded director Joel Souza.

According to investigators, David Halls, the assistant director, handed Baldwin the loaded .45 pistol during a scene rehearsal and told him it was ‘cold’ - meaning safe.

Halls later told investigators that he did not know there was a live round inside.

The guidelines also state that someone trained in firearms safety procedures should be on site to guide actors and those handling the gun.

'No one shall be issued a firearm until he or she is trained in safe handling, safe use, the safety lock, and proper firing procedures,' according to guidelines. 

According to an insider with knowledge of the set, several crew members on the set had taken several prop guns out the morning of the incident to go 'plinking' - a hobby in which people shoot at beer cans with live ammunition to pass the time.

The individual, who spoke on condition of anonymity to The Wrap, added that the round of unsanctioned target practice occurred just hours before Baldwin discharged one of the weapons and shot both Hutchins and Souza.

The weapon was one of three prop guns that the film's rookie armorer, Hannah Gutierrez-Reed, 24, had set up outside the set location on a gray cart, in the desert near the city of Santa Fe.

Attorneys representing Reed suggested that a disgruntled film crew member may have planted the live round that killed Hutchins inside a box of prop ammunition in a bid to 'sabotage' Baldwin's film.

In the wake of the fatal shooting, several crew members have come out claiming that they were overworked and denied hotel rooms in the vicinity of the New Mexico set. 

Gutierrez Reed's attorneys floated the theory that one of those 'disgruntled' crew members may have planted the live round on set as an act of revenge, during an interview with the Today show's Savannah Guthrie on Wednesday.  

'I believe that somebody who would do that, would want to sabotage the set, would want to prove a point, want to say they're disgruntled, they're unhappy,' Jason Bowles said. 

 'And we know that people had already walked off the set the day before... and the reason they are unhappy is they're working 12 to 14 hour days, they are not given hotel rooms in and around the area, so they had to drive back and forth an hour to Albuquerque, and they're unhappy.'

Bowles said his client was unaware that any live bullets were loaded into the gun  before the deadly October 21 shooting near Santa Fe, New Mexico. 

Gutierrez Reed has not been named a suspect, or charged with any crime in connection with Hutchins' killing, but she retained legal representation.   

'There was a box of dummy rounds, and the box is labeled "dummy,'" Bowles said. '[Gutierrez Reed] loaded rounds from that box into the handgun, only later to find out - she had no idea - that there was a live round.'

The armorer then handed the vintage Colt pistol to assistant director David Halls, who, in turn, passed it on to Baldwin and announced 'cold gun,' indicating that the weapon was safe to use, according to authorities investigating the deadly October 21 shooting near Santa Fe, New Mexico. 

'We're assuming somebody put the live round in that box,' Bowles told Guthrie. 'The person who put the live round in the box of dummy rounds had to have the purpose of sabotaging the set. There is no other reason you would do that: that you would mix that live round in with the dummy rounds.' 

Gutierrez Reed's other attorney, Robert Gorence, revealed that while the Colt had been locked away in a safe, the box of dummy ammunition was in a prop truck, which was 'completely unattended at all times, giving someone access and opportunity.'

Gorence also said that after the armorer retrieved the gun and loaded it with the rounds from the box, it was left unattended on a trey for two hours ahead of an afternoon film shoot.

Gutierrez Reed's lawyers defended her actions that day, saying that the loaded gun was not in her care for the entire duration of the filming because she was expected to perform two jobs on set: as an armorer and a props assistant. 

Bowels said that after lunch, Gutierrez Reed handed the gun she had loaded earlier to Halls and then went about performing her other duties as a props assistant.

As she handed over the Colt, the lawyer said Gutierrez Reed spun the chamber to show Halls the rounds inside.