Agree, 2-p. In theory, if the circle joint was properly fitted and kept properly clean and lubed, off-face more than one and a half thou would take a frightful lot of cycles of the action. I think better fitting and more use of "draws" is one thing that allows target O/U's to go so many rounds without coming off-face. Purdeys, BTW, has a replacable circle draw dovetailed into the action and available as a spare in thousandths increments - neat!!