An employee was helping a coworker unload drums using a drum dolly. The coworker had secured the 800 lb. drum to the 1000 lb. capacity drum dolly. As the coworker attempted to tilt the drum dolly back, the employee placed his hand on the back side of the drum. The drum then slipped off the dolly, which in turn fell back into place and caught the employee's hand between the drum being lifted and another drum that was still on the truck. The employee suffered a partial amputation of the right middle and ring fingers.