Case guages
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“I have a set of the Hornady case gauges that are used with the comparator. Naturally, I use them with setting up sizing dies for FL sizing dies such as for my AR. Is it necessary to use them to set up dies that only neck size? I neck size only and fire form the brass for specific bolt actions and am wondering if shoulder set back is an issue to consider in this case”.
For most reloaders on reloading forums there is no correlation between the case gage and the sizing die adjustment. those that use the L.E. Wilson cases gage use their fingernail to check protrusion then adjust the die to set the shoulder back a minute thousandths, I cut out all the wild and crazy guestimates, I go straight to the feeler gage (thickness gage).
I make datums, not difficult, understanding the use of ‘the datum’ is, for most the datum is a line on a flat sheet of paper, the Wilson case gage has a datum, drop a case into a Wilson case gage, like magic, the case sets on a datum, not a shoulder, a datum, again, I make datums, I also make shoulders, If I do not have a datum, I use a shoulder, that is possible if the reloaders understands the relation between ‘a datum’ and ‘a shoulder’.
When using the Hornady case gage measure the case length from the head of the case to its shoulder/datum first (before firing), then measure again again after firing. the difference between the first measurement (minimum length case) and second (fired case) will indicate the effect the chamber had on the case when fired. The difference in length"? I am the fan of transfers and standards, a reloader should know and understand full length sizing back to minimum length, a press, die and shell holder when adjusted to full length size a case to minimum length is restoring the case length from the case head to the shoulder, a reloader with a case gage and or a Sinclair/Hornady case gage should be able to measure the case length of a new factory minimum length case, the relopader should be able to measure a fired case that was fired to form, the reloader should be able to measure the length
of a case that has been fired and full length sized, after comparing all three measurement the reloader should know how how adjust the die for sizing, again, I am the fan of transfers and standards,
and I verify my adjustments.
Neck size only? I size cases to fit the chamber from the bolt face to the shoulder of the chamber, I am the fan of cutting down on all that case travel. I have neck sizing dies, I do not use them, I use the versatile full length sizer die. By adjusting the versatile full length sizer die off the shell holder I control the length of the case, I am not concerned with a small amount of air between the chamber and case, I am the fan of ‘time is a factor’
To your question, if you are fire forming and not using a full length sizer die there is no shoulder set back, when using a neck sizer die.
