So many factors come into play at that distance, variable wind speeds and directions, the up or down angle of the shot, the rotation of the earth, the bullets spin drift, the air pressure, air temperature, the temperature of your gun powde, humidity, lot to lot inconsistencies in your gun powder, cases, bullets, primers, etc, a clean bore vs a fouled bore. Everything matters at that distance.
Sprinkle in just a pinch of luck...
Bad luck for Musselman, good luck for civilization.