You have to manage your breathing.
YOUR BREATHING.
There's a fine line between not enough realism, and too much.
Try laying on your stomach and keeping a long, generally rifle shaped object steady while you take deep breaths.
OF COURSE you have to manage your breathing in a dedicated sniping game. Here's a list of things that affect the bullet's trajectory alone in long range sniper shots:
- Wind
- Gravity
- Shape of the bullet
- Type of bullet
- Weight of the bullet
- Speed of the bullet when it leaves the barrel
- Humidity
- The rotation of the earth
- Temperature
You think that BREATHING MANAGEMENT is over the top?