EE WAS WAITING IN A YOUNG BUGGY AT 32W 1000 AT THE FAN DISCONNECT SWITCH. A ROUND HAD BEEN SHOT SOME 700 - 800 FEET FROM THE EE. HE WAS AROUND CONERS AS WELL. A ROCK JARRED LOOSE FROM THE BACK AND STRUCK HIS RIGHT ELBOW. HE FELT PAIN AND TINGLING IN HIS RIGHT ARM. RETURNED LIGHT DUTY.