Headspace Gage Measurements

Q. I bought a headspace micrometer gauge from another manufacturer (not Forster) and then purchased a set of Forster Headspace Gages. I then measured the Forster Headspace gages in the micrometer gage and it consistently showed the set of Forster gages as .0035 inches shorter than the nominated size in 308 Winchester caliber. Am I doing something wrong? How do I resolve this issue as I now have two devices which will give me different results? I have not contact the other company as of yet.

A. The micrometer gauge to measure headspace of a cartridge case is very useful to obtain relative measurements of the headspace of any brass case. However, it is not an accurate gage to give a certified exact measurement. In other words, one may use a Forster gage to set the micrometer gage “to zero” but the relative measurement gage may not be used to measure the Forster calibrated, known dimension gage.

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