A shotgun is a good weapon, but really works best when your target does not have any armor. Anywhere else will kill him. Sniping is not camping. If you are sniping, you are aiming for a target, or multiple targets in a relatively large open area where movement is minimal and aim is critical. Camping is the unskilled act of hiding in an area where a target is unlikely to be visible and simply waiting for an enemy to stumble into a trap.
Camping is for the unskilled.
But it is still legal. All's fair in love and war. Watch your health. If you get shot, that health is gone for the rest of the round. Pulsate your firing.