Real guns can safely be used on movie sets so long as protocols are followed, US actor Matthew McConaughey has told AFP in an interview, as calls mount to ban firearms from filmmaking in the wake of the deadly "Rust" shooting.

Nearly 80,000 people have signed a petition to permanently remove firearms from sets after Alec Baldwin fatally shot a cinematographer on the New Mexico set of the low-budget Western last week.

Baldwin fired the Colt .45 during a rehearsal after being told it was safe, with the man who handed him the gun later admitting to police he had not fully checked it for live rounds.

"There's a safety protocol, and if it's followed, it can be safe on set," McConaughey said Thursday in the interview, conducted via Zoom.

The Oscar-winning "Dallas Buyers Club" actor described the incident as a "horrible accident that could easily have not happened."

"I've been on many sets where I'm dealing with firearms. There is an understood protocol. When any firearm is handed from one person to another, when it gets on set, there's a means of communication," he said.

"One of the beautiful things about how film sets work -- the organization is incredible. And they missed protocol. Somewhere. I don't know if they were in a rush."

The "Rust" armorer responsible for weapons on the film set said Friday she has "no idea" why there were live rounds present.

Prosecutors have refused to rule out criminal charges including against Baldwin, who was a producer on "Rust" as well as the lead actor.

Baldwin had been told by assistant director Dave Halls that it was a "cold gun" -- industry lingo for an inert firearm.

While not criticizing Baldwin, McConaughey said he "personally would try to always take even more steps" as an actor using a gun, including checking the weapon himself.

"You hear 'cold' -- now I want a visual," said the Texan star.

"If you and I are in a scene together, I need to give you visual. If it's a six shooter, do you see light through all six holes? Let me look you in the eye, you confirm, and you yell it out, 'cold.'"

He added, "You can't over-confirm it."

Advocates of a ban of real firearms on Hollywood sets say that gunshot effects such as the loud bang and muzzle flash can easily be added to fake rubber guns in post-production with modern technology.

"What do I think about that? I think you should follow protocol. And it should be non-negotiable," said McConaughey.