Your heart pumps ice water, and this soon applies to those you shoot as well. When you put a mook down, or when a named character fails a DeathTest caused by one of your Guns attacks, you can decide how bad you want to hurt them. The least damage you can do is such that they will rise bruised but unhurt and awaken after a few minutes (they keep all Wound Points, but ignore the result of the Death Test), and the worst you can do is a Death Test outcome of -10 (dies within 6 minutes). If you want to do worse than that, you have to use the normal rules.