I have reamer prints for almost every chamber reamer I own. When I'm Chambering if the chamber does not come out the same size as the reamer I know I messed up. A reamer is a form tool, If your setup is not correct and you try to cut that chamber your going to get an oversized chamber, It might be concentric but it will be oversized. Lots of ways to mess it up and lots of ways to cut it right, but knowing the difference is the biggest battle.
