D-L,
Look forward to seeing your work!
The finger rest isn't actually, it's the "second trigger";
As you bring the pistol up, you pull this trigger back for a tight grip, and this cocks the revolver. To fire, all you do is then pull the top or 'normal' trigger.
If the shot isn't taken, you just release the lower trigger and it goes back down onto the "safe" position, with a bar blocking the hammer. It's faster than a single action, and a nice light pull, unlike most double actions.
In use, it's faster than a double action. In my mind, it's the best thing since sliced bread!
Not a flimsy design either, as this revolver was rusted and beaten to death, but still functions and timed dead on.