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Rifles, Reloading, Optics, Equipment
Reloading
Head space ???
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<blockquote data-quote="woods" data-source="post: 538395" data-attributes="member: 6042"><p>First thing you need to realize is that it takes 3 to 4 firings on a case (with normal loads i.e. not low pressure not high pressure) before the case will expand fully to fill the chamber and have a "crush fit" at the shoulder. Here is a typical set of measurements on my 30-06 Steyr</p><p></p><p>new case - 2.040" </p><p>once fired - 2.0485" (then neck sized only with Lee Collet)</p><p>twice fired - 2.050" (again only neck sized)</p><p>3 times fired - 2.0510" (slight crush fit, neck sized only)</p><p>4 times fired - 2.0515" (crush fit, neck sized and size body and bump shoulder with Redding Body Die back to ~2.0510")</p><p></p><p>So until you have fired each case enough to fully expand the case those case measurements will be in flux.</p><p></p><p>Second thing to realize is that when you size the case body at all the case body will squeeze like a baloon and push the shoulder forward. The only thing that will prevent the shoulder from moving forward is if you have the FL die or body die adjusted down far enough to start pushing the shoulder back.</p><p></p><p>So the ideal sizing is to neck size until you get the crush fit and then push the shoulder back .001". Do this on every subsequent firing/sizing and then you have a case that is as close to exactly the same dimensions everytime as you can get it.</p><p></p><p>Then you just need to regulate your annealing so your bullet grip will be as consistant as possible.</p></blockquote><p></p>
[QUOTE="woods, post: 538395, member: 6042"] First thing you need to realize is that it takes 3 to 4 firings on a case (with normal loads i.e. not low pressure not high pressure) before the case will expand fully to fill the chamber and have a "crush fit" at the shoulder. Here is a typical set of measurements on my 30-06 Steyr new case - 2.040" once fired - 2.0485" (then neck sized only with Lee Collet) twice fired - 2.050" (again only neck sized) 3 times fired - 2.0510" (slight crush fit, neck sized only) 4 times fired - 2.0515" (crush fit, neck sized and size body and bump shoulder with Redding Body Die back to ~2.0510") So until you have fired each case enough to fully expand the case those case measurements will be in flux. Second thing to realize is that when you size the case body at all the case body will squeeze like a baloon and push the shoulder forward. The only thing that will prevent the shoulder from moving forward is if you have the FL die or body die adjusted down far enough to start pushing the shoulder back. So the ideal sizing is to neck size until you get the crush fit and then push the shoulder back .001". Do this on every subsequent firing/sizing and then you have a case that is as close to exactly the same dimensions everytime as you can get it. Then you just need to regulate your annealing so your bullet grip will be as consistant as possible. [/QUOTE]
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