Jim
I am not sure why yours were stuck so bad. I made a tool more or less like the one you have, and they came right out. I can't remember what steel I used, it was either 4140 HT or it was made from some other old tool that was similar. I think I may have used some heat to loosen them up a bit as well. The holding screw is the thing that really makes this tool work. The screw must have the same thread pitch as the ring for it to work in the best possible way. Another thing that works well with things like this, is to tap on the end of the tool while applying torque to loosen the ring.
I am not sure why yours were stuck so bad. I made a tool more or less like the one you have, and they came right out. I can't remember what steel I used, it was either 4140 HT or it was made from some other old tool that was similar. I think I may have used some heat to loosen them up a bit as well. The holding screw is the thing that really makes this tool work. The screw must have the same thread pitch as the ring for it to work in the best possible way. Another thing that works well with things like this, is to tap on the end of the tool while applying torque to loosen the ring.