One bugbear of a weapons specialist who works on films that I know is when the hero keeps shooting when the gun would be out of bullets. Because he knows exactly how many each magazine would take, it drives him nuts. Glad I am ignorant on such matters.

And yes - a lot of the designer cuts and injuries in action movies are ridiculous. With the ludicrous beatings some of these characters take, they'd either be dead or at the very least covered in bruising, unable swollen, to see out of their eyes, etc.