I am sure Talley rings come from the factory at least as true as manufacturing tolerances allow. The problem is the rifles we mount them on are not perfectly true. You most likely could take those same Talleys and mount them on another rifle of the same model and have different results just due to manufacturing tolerances at different production times, different milling machines/lathes and drill and tap operations used between individual rifles, etc. This is known in the machinist world as "stacking of tolerances". This is true even for a quality manufacturer like Cooper, who I own three of their rifles.
