Gauge R&R

Before trusting any measurement you have to know how much of the variation is the gauge rather than the parts. Repeatability (same operator, again) and reproducibility (different operators) combine in quadrature. Under 10% is acceptable, over 30% means you are mostly measuring your own measurement system.

Enter standard deviations, not ranges. %GRR against tolerance is what matters for a pass/fail gauge; %GRR against study variation is what matters for process studies — they can disagree, so report both.