He pulled back the hammer, aimed at the cinematographer, pulled the trigger and blasted her in the chest.
And none of those actions was in the script or rehearsal.
He was practicing a fast draw. Cocking the hammer is part of a fast draw with a single action revolver.
However, he should have lowered the hammer down on the chamber, not pointed it at someone and pulled the trigger.
And none of it in the MSM either.