The key to a correct revolver grip is the placement of the trigger finger, and the key to fast revolver shooting is to keep the trigger finger square on the trigger (1) throughout its entire arc of movement. You never want your finger to leave the face of the trigger anywhere during the firing sequence. Get your hand as high as you can on the grip and still have the revolver functional. The web of the shooting hand is over the back strap (2), so when you fire you have enough clearance for the hammer to cycle. You want the centerline of the bore to be close to the centerline of your hand. Your hand is high on the grip with the barrel held low. Use of the non-firing hand is 70% of the control of the revolver. Use both thumbs, wrap them over, and pull tightly. The big thing is consistency to the presentation of the target.