i will grant you that there are limits of the eyeball...but its very small.
in true benchrest competition....targets are measured by the second method or similar, and then checked. when a record is believed to be set the targets are sent off to a committee.......it is actually amazing the small variation one comes up with when you have done it a few( hundred) times. br results are often seen in 4 decimal places.....this is an average of 5 three decimal targets......not an actual 4th decimal measurement.
and for the record a 308 bullet/or boolit does not always make a 308 dia hole......lots of variables there....but it is accepted as part of the game.
your 'ACCURACY" is your guns average...not the one time wonder group.
and since when is a 45 460 ??? 452 and 454 but not seen a 460 actual dia ???