Once you've progressed far enough into the game to have unlocked the Six Shooter revolver (by defeating the Cowboy Security Guard Psychopath in the South Plaza) it's a good idea to carry his weapon around, which can be found on the sawing board he dies on. You can only have one at any time like all Psychopath weapons, so if you try to exit and re-enter the area to get an extra Six Shooter, you won't find anything on there until you lose the one you're carrying (or that your Co-Op partner is carrying). This weapon is incredibly powerful, more so than any rifle other than the Sniper Rifle. And it also has a great rate of fire. With this weapon you can easily take out most Psychopaths by simply corner shooting, or in some cases just continually shooting them as most Psycho's will be stunned for a brief moment by each shot.