EE WORKING RIB BOLTING W/OTHER WHEN THEY WERE PUTTING RIB GUN DOWN. OTHER DROPPED HIS END BEFORE EE DID. EE WAS HOLDING GUN W/LEFT HAND. HE JERKED IT HAND AND ARM. THOUGHT ARM WOULD BE OK, THE N ON 7-21 NOTICED SWELLING AND BRUISING DX-LT ARM BICEP TEAR. TURNED IN LATE DUE TO WAITING ON MEDICAL RPTS AND INFO TO CONFIRM INJURY.