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Rifles, Reloading, Optics, Equipment
Reloading
FL sizing ?
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<blockquote data-quote="Bill Johnson" data-source="post: 1062492" data-attributes="member: 84129"><p>It appears you might be operating under the assumption that nothing has changed dimensionally on the case after being fired. That is never the case. </p><p> </p><p>Unless, on chambering, you are crush-fitting the cartridge in the chamber, it should (will) grow, if only ever so slightly. </p><p> </p><p>It has to have clearance in the chamber.</p><p>Upon firing, it expands, first at the neck sealing the chamber, then the body expands laterally to fill the chamber circumferentially, then, as maximum pressure is reached, the case head is forced aft, stretching the case. It may appear to fit a case gage the same, and with dies set up for minimal sizing, will limit growth to .001 or so, but it will grow.</p><p> </p><p>Current practice is to set up dies for bolt rifles so the shoulder is set back .002" during sizing to provide for proper chambering but limit case stretching. Autoloaders, it's recommended to set back shoulders .003 - .004.</p><p> </p><p>An effective way to measure shoulder position is to use an appropriate size bushing and a caliper:</p><p> </p><p><a href="http://s813.photobucket.com/user/Dollar_Bill_2009/media/3006gaugingheadspace2.jpg.html" target="_blank"><img src="http://i813.photobucket.com/albums/zz53/Dollar_Bill_2009/3006gaugingheadspace2.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></a></p><p> </p><p>For the 30-06, a standard 3/8" bushing from Home Depot or Lowes fits the bill perfectly. </p><p> </p><p>You measure the case as shown before and after firing. In this instance, the case shoulder-to-case head distance increased .003. </p><p> </p><p>If I'm way off base on this, WhiteOak, just let me know. It wouldn't be the first time I went on and on about something unrelated to an OP's post. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p></blockquote><p></p>
[QUOTE="Bill Johnson, post: 1062492, member: 84129"] It appears you might be operating under the assumption that nothing has changed dimensionally on the case after being fired. That is never the case. Unless, on chambering, you are crush-fitting the cartridge in the chamber, it should (will) grow, if only ever so slightly. It has to have clearance in the chamber. Upon firing, it expands, first at the neck sealing the chamber, then the body expands laterally to fill the chamber circumferentially, then, as maximum pressure is reached, the case head is forced aft, stretching the case. It may appear to fit a case gage the same, and with dies set up for minimal sizing, will limit growth to .001 or so, but it will grow. Current practice is to set up dies for bolt rifles so the shoulder is set back .002" during sizing to provide for proper chambering but limit case stretching. Autoloaders, it's recommended to set back shoulders .003 - .004. An effective way to measure shoulder position is to use an appropriate size bushing and a caliper: [URL="http://s813.photobucket.com/user/Dollar_Bill_2009/media/3006gaugingheadspace2.jpg.html"][IMG]http://i813.photobucket.com/albums/zz53/Dollar_Bill_2009/3006gaugingheadspace2.jpg[/IMG][/URL] For the 30-06, a standard 3/8" bushing from Home Depot or Lowes fits the bill perfectly. You measure the case as shown before and after firing. In this instance, the case shoulder-to-case head distance increased .003. If I'm way off base on this, WhiteOak, just let me know. It wouldn't be the first time I went on and on about something unrelated to an OP's post. :D [/QUOTE]
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