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Rifles, Reloading, Optics, Equipment
Reloading
Case Head Seperation and Brass Growth at Resizing
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<blockquote data-quote="woods" data-source="post: 771373" data-attributes="member: 6042"><p>Like AZ said, you are oversizing</p><p></p><p>Typically a case shoulder will move ~85% toward being in contact with the chamber shoulder on the first firing. Then it will take additional firings to where it will contact the shoulder and cause a crush fit</p><p></p><p>For example here is a typical string of measurements on a 30-06 with close to max loads where I neck sized only until I got the crush fit (the measurements themselves don't matter, just their relationship to each other), measurements taken with a Hornady comparator attached to calipers</p><p></p><p>New case - 2.040"</p><p>Once fired - 2.0485" (neck sized only with Lee Collet)</p><p>Twice fired - 2.050" (neck sized only with Lee Collet)</p><p>3 times fired - 2.051" (slight crush fit, still neck sized only with Lee Collet)</p><p>4 times fired - 2.0515" (crush fit, neck sized Lee Collet, shoulder pushed back Redding Body Die)</p><p></p><p>After the crush fit you need to push the shoulder back only .001" or so. That will give you a very slight crush fit and keep your brass from overexpanding each firing and being overworked.</p><p></p><p>If you are pushing once fired brass shoulders back .010" then you probably have headspace on those sized cases of .012" or so, and that is waaay too much. Case head separations are predictable with that practice.</p></blockquote><p></p>
[QUOTE="woods, post: 771373, member: 6042"] Like AZ said, you are oversizing Typically a case shoulder will move ~85% toward being in contact with the chamber shoulder on the first firing. Then it will take additional firings to where it will contact the shoulder and cause a crush fit For example here is a typical string of measurements on a 30-06 with close to max loads where I neck sized only until I got the crush fit (the measurements themselves don't matter, just their relationship to each other), measurements taken with a Hornady comparator attached to calipers New case - 2.040" Once fired - 2.0485" (neck sized only with Lee Collet) Twice fired - 2.050" (neck sized only with Lee Collet) 3 times fired - 2.051" (slight crush fit, still neck sized only with Lee Collet) 4 times fired - 2.0515" (crush fit, neck sized Lee Collet, shoulder pushed back Redding Body Die) After the crush fit you need to push the shoulder back only .001" or so. That will give you a very slight crush fit and keep your brass from overexpanding each firing and being overworked. If you are pushing once fired brass shoulders back .010" then you probably have headspace on those sized cases of .012" or so, and that is waaay too much. Case head separations are predictable with that practice. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Case Head Seperation and Brass Growth at Resizing
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