In this scenario though, it is unrealistic to expect the actor to carry out a thorough inspection to make sure it is safe and unloaded too. The responsibility falls on the the prop team and the individual who confirmed it was safe (when it in fact, was not).
What? Why is that unrealistic? It takes a few seconds at most and is a really basic thing to do in pretty much any other circumstance. Army recruits in phase 1 training with a reading age of 11 can manage to do this, I don't see why that would be an issue for a highly paid movie actor, especially one with decades of experience.
Actors literally go on courses where they learn stage combat, use of weapons etc.. basic weapons safety really ought to be a thing.
Hopefully this will change how it’s done and everyone who is passed a firearm will check and be seen to check it. It needs both the person receiving the firearm and the person handing it over to confirm the recipient has checked it.
Exactly, in fact, perhaps have the actor load it him/herself.
Generally it is recommended that actors handling firearms are familiar with checking them:
https://www.actorsequity.org/resources/Producers/safe-and-sanitary/safety-tips-for-use-of-firearms/
Yup, he seems to have failed to adhere to these two basic points for a start:
"Treat all guns as if they are loaded and deadly.
[...]
Never point a firearm at anyone including yourself. Always cheat the shot by aiming to the right or left of the target character. If asked to point and shoot directly at a living target, consult with the property master or armorer for the prescribed safety procedures.
It's still not clear if this was during a scene or if he's simply discharged the firearm accidentally on set, likewise there is some muddled reporting re: a live round and whether they're talking about an actual live round or if that's just a reference to some movie set terminology re: blanks too.