No. The gun was tested. I won't fire with a partially cocked hammer. You can rapid fire (fan) a single action revolver like that but the hammer needs to fully cock and then the trigger needs to be pulled.
I have read a few things that are not in AB's favor. He was a producer and apparently the shoot was being run understaffed. People were getting 3-4 hours of sleep a night. The "armorer" was inexperienced and also doing props. Two jobs. AB, according to statements, refused an offer by the armorer to teach him how to use a single action revolver. Not good. The gun was NOT handed to him by the armorer. It was the AD that handed him the gun and pronounced it cold. Which carries about as much weight as the caterer declaring the gun is cold. AB probably should have known better. Because the shot was looking into the barrel of the gun, I am assuming that the gun was supposed to be loaded with dummy rounds. Dummy rounds have a dimpled primer, holes drilled in the case and BB's inside the case (for a rattle test) but have a real bullet crimped to the case. Like I said, this is done so when you are looking at the gun from the business end, you can see the bullets in the cylinder instead of empty charge holes.
When handed the gun, AB, in order to check it, would have to put the hammer in a partially cocked position, opened the loading gate and rotated the cylinder to check for six dimpled primers. (or empty charge holes) If he's going that far, the gun should probably be emptied and reloaded so the dummy rounds (as opposed to blank rounds) can be thoroughly visually inspected for the holes in the case, shake test, dimpled primers etc. In which case there really is no point in handing them a gun with dummy rounds loaded into the cylinder. Give them the gun and the dummy rounds and make them load it from scratch.
It is possible to make an old Colt 45 single action fire without pulling the trigger. In order to carry those guns safely they used to only load them with five bullets and leave one charge hole empty. Hammer was lowered onto an empty charge hole instead of on top of a live round. This was done because a hard blow to a fully lowered hammer could cause the hammer to move forward and strike firing pin/primer. Newer single actions have eliminated this problem.
They found 27 live rounds spread around the set. One of them was in AB's bandolier.
I still think this should have been a civil case. But the victim's family has already settled. They're going forward with the movie. The armorer has also been charged along with AB.
The live rounds thing is ridiculous. But, live rounds happen in the real world, so I suppose you have to inspect virtually each and every round multiple times to guard against this kind of thing. Not my problem, thank heavens.