I have a stop that I made from an old spark plug. With the center electrode removed drill and tap from the side for a set screw. I think a long 5/16th bolt will work through the center for a stop. Rotate to stop both directions middle is what you want.
The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD