EE WAS OPERATING THE ROOF BOLTER ON LEFT SIDE & HIS C0-WORKER WAS TRYING TO UNPLUG A DRILL STEEL BY STRIKING ANOTHER DRILL STEEL AGAINST IT. THE INSERT FLEW OUT OF THE END & WENT ACROSS, STRIK ING EE. CAUSE OF INJURY WAS AWARENESS & COMMUNICATION. COMPLIANCE WITH RULES/REGS NOT A FACTOR; MINER KNOWLEDGE A FACTOR; MINING EQUIP/SYSTEMS NOT A FACTOR; SAFETY EQUIP. O.K.