Yoopersup, please direct me to the thread (and user name of the person) where somebody said you could use the screw in the clamp to ground a box (while still being used for the clamp). All I can find is people saying that the screw does not need to be green.
The NEC (which is what you must abide by) does not require the screw to be listed for the purpose. Standard 1/4-20, silver colored bolts are "legally" used everyday to attach ground lugs to boxes.
Are you strictly a residential electrician? If you where used to large commercial jobs with heavy gauge wire then the thought of a ground screw needing to be listed would not even cross your mind.
