I was reading about the wall drill and realized that it will have value for me.
I was also thinking about the further value that it may have if a highlighter or crayon were shoved in the barrel and placed o so lightly on the paper. When the trigger is pulled it should show any little twitch that you might have?
Just a random thought. I need to pass my quals so I am racking my brain to get the little tweaks out of my shot placement.