Good morning! Sorry so late to reply you.Regarding the smaller (fine) holes, usually, we use the pin gauge to inspect the inner hole, later our QA team did the spot check by projector in the location dimension, after the qualifying, we did the package to ship out at last.We are sorry for the slightly smaller holes which you feedback, do you mean the D0.315 (+0.045/+0.025)? Do you mind to send us your gauge photo, inspecting photo, and lt will be great helpful for us, thank you.