How to Get the 'For Whom the Shell Tolls' Achievement in Modern Warfare 3

If you're a good shot, this is the achievement for you. In Call of Duty: Modern Warfare 3 on the "Back to the Grid" level, you gain access to a mortar to hold off a few waves of enemies. But the trick to getting the achievement and 20G, or bronze trophy if you're on PlayStation 3, is to take out all of the bad guys using only four shells.

Ray and Mike from Achievement Hunters show you how to make the most of those four shells, as well as giving advice for specific timing and the best places to aim your mortar.