WB
FIrst off if you can measure a hole with calipers you are
Wednesday, March 04, 2020, 10:55

a better man than me. I find it almost impossible to get consistent measurements to 0.001" or 0.0005" using calipers. The very best method to truly test is using "pin gauges". Try the gauges until you find a size that will not push through. It's the next smaller size. At best one can force soft lead slugs through the holes and then measure the slugs with calipers or micrometers. I've had some success with that, but you need to keep 6 holes, 6 lead slugs, separated and be very diligent.

Getting a real measurement can be a bit more difficult that one might initially think.