How to aim and shoot with pistol in Assassins Creed 4?
Solution 1:
Make sure you have Pistols selected, by hitting "4". Then make sure they are reloaded, hit "R" Make sure you have Bullets, should be a number other then 0 by the pistol Icon.
Now you are good to go, Press and hold the "Right Mouse Button" to aim, use your mouse to move your crosshairs. click "Left Mouse Button" to fire. You can also auto fire at a highlighted target by pressing "f"