01-13-2022, 01:08 PM
The actual numbers are irrelevant. Measure your fired brass, adjust sizer using the same gauge, to achieve desired bump, usually .002-.003. The gauges are for getting a reference point. If you had a non adjustable bathroom scale that you knew read 5 lbs off, it does not matter over the long haul. 200lb one month v 210lb the next month guess what you gained 10 pounds regardless.
Straight from Sinclair "Rather than measuring to the datum line, these gauges indicate off of the shoulder of the case to get a better, more easily assessable measurement of how much you are actually sizing your cases."
One type of gauge uses a specific diameter of hole like Hornady, .330/.350/.375/.400, then Sinclair that just matches the shoulder angle regardless of diameter.
Oh and here is a HUGE BTW! When you measure your brass from your chamber make sure it was a mild load. Brass flow at the ejector hole or extractor cut or a cratered primer will TOTALLY jack your readings! Especially cratered primers, they will add 3-5 thou, you adjust for 4 thou bump, and you actually end up with zero bump. Because you are now measuring a primerless case.
Straight from Sinclair "Rather than measuring to the datum line, these gauges indicate off of the shoulder of the case to get a better, more easily assessable measurement of how much you are actually sizing your cases."
One type of gauge uses a specific diameter of hole like Hornady, .330/.350/.375/.400, then Sinclair that just matches the shoulder angle regardless of diameter.
Oh and here is a HUGE BTW! When you measure your brass from your chamber make sure it was a mild load. Brass flow at the ejector hole or extractor cut or a cratered primer will TOTALLY jack your readings! Especially cratered primers, they will add 3-5 thou, you adjust for 4 thou bump, and you actually end up with zero bump. Because you are now measuring a primerless case.