OPERATING A ROOF BOLTER MACHINE, WHEN STARTING A DRILL STEEL IN THE MINE ROOF, THE STEEL BENT WHICH RESULTED IN HIS RIGHT SHOULDER BEING JERKED. PAIN & STIFFNESS RESULTED FROM THIS ACCIDENT. HE CON'T TO EXPERIENCE DISCOMFORT, AN MRI WAS TAKEN IN 2/04 DETERMINED HAD A TORN ROTOR CUFF. BEGAN MISSING SCHEDULED WORK DAYS 3/16/04. BECAME A REPORTABLE INJURY ON THAT DATE.