From Slate:
Gravity can move a pellet of birdshot lower in your body, at least until enough scar tissue has built up to hold it in place. If the pellet ends up in a hollow organ like the stomach, it can jostle around or make its way through your digestive tract. Bullets in the brain seem to pose an especially serious risk of further injury—people who get shot in the head have to worry about "moving bullet syndrome."Technorati Tags: slate, cheney, birdshot
Bullets or pellets can also move around in your bloodstream. If a pellet manages to pierce one side of a blood vessel but not the other, it might get swept into circulation. The smaller the projectile, the more likely it is to move around in the blood. Heavier bullets tend to migrate downward, while a tiny pellet might be carried along toward the heart. In 1992, the Associated Press described a man who had been shot in the left side of his face. A fragment of the bullet had lodged in his jugular vein; doctors finally removed it from one of the chambers of his heart.