shoulder measurements from gage 1458 1464 1460

Here’s how case shoulders can vary, and why resizing them is so important to accuracy. Here, at left, a brand-new case measures 1.458 inches to the shoulder. Middle, a fired case measures 1.464 inches. Left, your die setting should be 1.460 inches.

4 thoughts on “shoulder measurements from gage 1458 1464 1460”

  1. Using the Hornady shoulder gages, I have set up my dies this way. Measuring a number of them after sizing, they tend to vary a thousandth or two either way of the ideal value desired, due to temperature, etc. Should a person set up the headspace so the maximum length measured over a number of cases is the correct headspace calculated, or lock the die down so that the average result is the desired value expected?

    1. It depends – if you are reloading for a bolt action gun, being a little “tight” is not so critical since, as the article mentions, you can go down as low as .001 for set-back. However, if you are reloading for a semi-auto and you are setting headspacce based on the average shoulder set-back, all it takes is one cartridge with not enough headspace (less than the .003″ (clean chamber) or .004″ (recommended in this article) ) to cause chambering and possible “slam-fire” problems. The downside of a little too much headspace is your brass gets a little too much work on firing and resizing, but the downside of not enough is a potential safety problem. So, if you are setting up for a semi-auto, set your die so that the minimum set-back ON ALL resized cases is .004″.

    2. There are so many variables – case brands, brass composition & thickness, dimensional tolerances in the resizing mechanism (press ram, pins, shell holder, dies, flex, etc.), number of times the cases have been resized, length when the cases were extracted, and the list goes on . . .

      In my experience, holding +/- 0.002″ is pretty darn good, and would set the die based on the average. As Mr. Zediker writes (paraphrasing), “never size to the maximum headspace”.

      1. Here is something I commented on from a later Zediker article, but really belongs here:

        Headspacing the case so that the case is a bit longer(less headspace) also positions the entire length of the case body closer to the walls of the chamber – think of a cone inside of a cone. This gives better alignment, and less yaw & pitch = less “wiggle” room = better precision. All the headspacing parameters that Mr. Zediker details in his writings still apply, but the dimensional physics also apply. Size your cases for absolute safety, then reliable operation, then best accuracy.

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