The 9.5 grain Exterminators were an outstanding pellet. The very first UK HFT championship was won by Tony de Cross? using them in a BSA SuperTen. The FAC HFT championsip was also won by a SuperTen prepared by Bowkett but I dont know what pellet was used. It was in .22".
If Bob's still around you might be able to contact him via Lea Valley club, he's a great guy who will do anything to promote air rifle shooting.
sorry to hear this