One thing that bothers me though is the way Watson is holding his gun. I am by no means an expert, so please forgive me if I make a fool out of myself...
Seeing as how Watson has been in the military, he would have received training, and they would have thought him to always keep your finger away from the trigger, as long as you don't have the intention to shoot. Holding your finger on the trigger can result in unwanted shooting when someone bumps into you, or when you get startled.
When you holding the gun, you indeed use your left hand to provide support (if you're right-handed). But as guns get hot when fired, you keep your support hand on the bottom of the gun, in such a way that the fingers of the support hand are on the back of the firing hand. That way your hand gives maximum support, without any change to burn yourself. Believe me, holding the gun in the right way will increase the total reality of this picture, and looks more professional as well.
This is just my view on it, but I hope you found it helpful for any future shots.