EE WAS UNSETING A HEATER TUBE INTO #5-2 VERTICAL HEATER. ROUTINELY, A 30# RIVET GUN IS MOUNTED ON THE TRAILING END OF THE TUBE TO HELP DRIVE THE TUBE IN. THE TUBE GOT STUCK AND EE USED A PAIR OF PLIERS TO TWIST THE TUBE IN AN EFFORT TO GET IT MOVING. THE TUBE DROPPED APPROX. 3' AND PINCHED EE'S RIGHT HAND BETWEEN THE RIVET GUN AND HEATER BAFFLE. FRACTURED RT. RING FINGER. EE IS ON