1810 England, the height of the Napoleonic wars. It was thought that humans walked the path of enlightenment leaving monsters and dark things behind. However, those monsters and night stalkers merely hide in the darkness, as a young maid, Bernadette, soon finds out.
Believe it or not, people don't necessarily fall down upon receiving a fatal gunshot wound. Even if they are shot in the head (of course this depends on where and how much of the brain is destroyed), a person is capable of standing and returning fire. I've heard of cases where a person didn't even realize they were shot until they were slipping in their own blood. In other words, movies and TV (westerns especially) and some comics are lying to you. For gunshots, the only reason a person would fall immediately would be because of the force of impact or because of shock (Guess which reason it is this time).
Incidentally, stomach wounds are perhaps one of the longer, nastier, more painful ways to die; first there's the blood loss and pain, but also leaking gastrointestinal juices and acids (acids that you would find in a car battery) added in.
@Superficial_Fox: By the way this is also true for pretty much any cutting weapon in history. If you are watching a fantasy and see mooks dying the instant sword touches their bellies, it's just Hollywood.
Aside from trauma form blut weapon to the head (and rarely even then), stab/arrow through eye, or beheading (that was nearly impossible in actual combat), killing somone instantly is just a myth (through there were cases of people fainting from mortal wound and bleeding to death).