Had this situation a few nights ago. 8-ball, I'm on the 8. The 8 and 11 are frozen on the rail almost touching. My opponent has just handed me the ball, giving me ball in hand. My goal was to create separation between the 11 and 8 and leave a tough shot. I placed the CB where indicated, and attempted to feather off the right side of the 8 with right english, going three rails back to the middle of the end rail. What actually happened was I hit the 8 too thick and the 11 went straight into the near corner pocket. The 8 came off the end rail a few inches and the CB went to the middle of the table. My opponent banked the 8 in.
Even if my shot had worked my opponent could still have played safe back. I was trying to do something other then just tap the 8 and have them hand the CB back to me again. We were not playing 3-foul rules.
What would you do?

Even if my shot had worked my opponent could still have played safe back. I was trying to do something other then just tap the 8 and have them hand the CB back to me again. We were not playing 3-foul rules.
What would you do?
