Wouldn’t you have to pull the hammer back until it hits a ‘click’ that holds the hammer back? Then you’d aim and pull the trigger. If his finger slipped before it fully cocked it could happen.
Have to pull the hammer all the way back for the cylinder to fully rotate to the next cartridge and go into full battery. The hammer won’t fall unless the trigger is pulled.
Yes, and I've also read where the trigger sear can get worn after use even if the "click" happens at half-cocked. Near as I can tell, Baldwin didn't get to the first (half-cocked) sear and it either slipped out of his thumb from sweat/oil and the hammer firing pin hit the bullet primer.
This is all on the armorer. However, if Baldwin did fire others according to the crew and brought in a novice armorer, he probably has some liability.