MSP, that would be .010 Which is 10 thousandths of a inch. A regular piece of note book paper is 3 to 5 thousandths. So, the shim was equal to two sheets of note book paper. The shim is not that thick. All I know is it locks up tight, the action does not pop open, and their is no vertical stringing. That does not mean their will not be. I would also venture to say that the lug was wore a little. Maybe someone was loading pretty hot. The lug area were it sets on the hinge pin was really shiny. Which idicated to me there was some were. I have been told and read on another post that the hinge pin itself is very hard. So loading ammo pretty hot could cause the lug to wear. IMO I would not think that the shim would wear out with normal loads.
BBF