“The revolver is the type of gun which doesn’t shoot before the trigger is pressed and Alec is partially guilty for causing that shot.”
Partially?
Well, you’re kinda right. I’m guessing what may have happened is; Baldwin, perhaps not familiar with single action revolvers, when he picked up the gun the hammer was down resting on the firing pin. When he picked it up and gripped it he unwittingly squeezed the trigger and continued to hold it pulled back. Then, when prepping for the scene still holding the trigger back he pulled the hammer back to the cocked position. Then, supposedly he was told by someone to release the hammer and when he did so being the trigger was pulled all the way back it struck the firing pin and fired. I own a couple of single actions and this is how you fan one. You can often see this done in old shoot ‘‘em ups of John Wayne, Roy Rogers, etc, era. Just a theory….