Swap Shot only works with non-rapid guns (for example, pistols or shotgun). To use Swap Shot, equip any of the following combinations: Pistol + Pistol, Pistol + Shotgun, or Shotgun + Shotgun. Your mouse also must have a scrollwheel in the middle. If you do not, you can use 2 and 3 but it is harder. When in battle, use you first pistol. Hold the LEFT MOUSE BUTTON. After the first shot, scroll down to your next gun. After that shot, scroll back up to the first gun. Do this repeatedly until your guns run out of ammo. Note: This move is part of K-Style, a technique used amongst the pros.