JC,
I did mean 0.1mm steps. A correctly sized pin will only enter the bore if it is properly presented and this does depend on the skill of the mechanic. So does the proper use of small hole gage depend on the skill of the mechanic. There are a great many more small bore gage sets around than pin gage sets, and they are considerably cheaper. Furthermore, one set of small bore gages will cover all the more common barrel bores, but it would take two pin gage sets to span the diameters. You would need a precise measuring instrument to use small bore gages, whereas the pins themselves are the instruments. On the other hand, we all need a precise measuring instrument anyway, so that is not really an extra requirement. Pin gages come in .001" steps, but common micrometers read to .0001" on the Vernier. I guess what it boils down to is we just use the best tool we have, the best way we can.
Mike
