I'm not sure if I am posting this in the right place or not. But here goes. I am about to assemble the bottom end of my 383 SBC. I have an old NSK metric bore gauge. Very nice unit. The ball points are free and rolling. I want to check rod and main bearing clearance. I have always just used plastigage in the past due to lack of equipment. Now I have the equipment and want to learn how to use it. Never having done this before I did a trial with an old set of bearings. I can check clearances easily and accurately. The problem is that the wheels and points of the bore gauge are leaving marks on the bearing shells. These marks are not deep. You can't catch a fingernail in them, but you also can't rub them out. I don't think you could even call it a scratch. Just a mark. Even being as careful as possible, I can't measure without leaving marks. Anyway, I don't like it and don't want to mark the new bearings like that. Am I doing something wrong or am I being too anal? Thanks for any input, guys.