
(Of course I'm exaggerating...)
Here is my suggestion: Why not making an aiming mode to the pistols. Holding a button will aid the aiming of a pistol by slightly magnifying the scene (like from FOV of 90 to FOV of 82), decreasing the spread and maybe changing the cursor.
But the down side is that the player could not move, or if he is starting to run or walk, then aiming mode is aborted.
After all even in real life (or at least in brouce willice films) you need to stand, concentrate and aim to get the shot right.
If you worry about this encouraging what you call "camping" then... If I understand correctly, camping is staying in a hiding place and from there shoot everyone without getting out. Personally I think that who plays like this is a coward. However, its not bad to hide in houses, mines, in distant places behind or under boxes, just not all the time. The maps are filled with these places, they were meant to be "hiding places". If someone is feeling insecure to get out to the playing field - then thats his problem. Its just like in the real life...