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Rifles, Reloading, Optics, Equipment
Reloading
case head seperation?
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<blockquote data-quote="bigedp51" data-source="post: 550905" data-attributes="member: 28965"><p>The case expansion or bulge you see at the base of the case is the difference between the actual diameter of the chamber and the diameter of the cartridge case. The chamber diameter of the .270 is to be .474 and the case base diameter is allowed to be .473 to .463 by SAAMI manufacturing tolerances.</p><p> </p><p>Bottom line, the larger the diameter of the chamber and the smaller the diameter of the cartridge case the more pronounced this bulge will be.</p><p> </p><p>The headspace of each rifle and how far you full length resize the cartridge case and how the case is constructed in the web area determines case head separations.</p><p> </p><p>Below is an example of .303 British cases both fired in the same rifle, the case on the right has a smaller base diameter and expanded outward further than the case on the left.</p><p> </p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/privihxp.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p> </p><p>When full length resizing you only want to push the shoulder of the case back .001 to .002 to allow minimum chambering clearance. If you push the shoulder of the case back too far each time you resize the case it will stretch in the base web area to meet the bolt face each time the case is fired and case head separations will occur.</p><p> </p><p>If you reload proper fireforming and reloading techniques will help prevent case head separations. I use a RCBS Case Mastering Gage to check my cases for stretching and thinning in the web area.</p><p> </p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/IMGP6525.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p> </p><p>Below are helpful tools to use when resizing cases and only push the shoulder of the case back .001 to .002</p><p> </p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/7-17-201055522PM.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p> </p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054719PM.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p> </p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054345PM.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="bigedp51, post: 550905, member: 28965"] The case expansion or bulge you see at the base of the case is the difference between the actual diameter of the chamber and the diameter of the cartridge case. The chamber diameter of the .270 is to be .474 and the case base diameter is allowed to be .473 to .463 by SAAMI manufacturing tolerances. Bottom line, the larger the diameter of the chamber and the smaller the diameter of the cartridge case the more pronounced this bulge will be. The headspace of each rifle and how far you full length resize the cartridge case and how the case is constructed in the web area determines case head separations. Below is an example of .303 British cases both fired in the same rifle, the case on the right has a smaller base diameter and expanded outward further than the case on the left. [IMG]http://i122.photobucket.com/albums/o254/bigedp51/privihxp.jpg[/IMG] When full length resizing you only want to push the shoulder of the case back .001 to .002 to allow minimum chambering clearance. If you push the shoulder of the case back too far each time you resize the case it will stretch in the base web area to meet the bolt face each time the case is fired and case head separations will occur. If you reload proper fireforming and reloading techniques will help prevent case head separations. I use a RCBS Case Mastering Gage to check my cases for stretching and thinning in the web area. [IMG]http://i122.photobucket.com/albums/o254/bigedp51/IMGP6525.jpg[/IMG] Below are helpful tools to use when resizing cases and only push the shoulder of the case back .001 to .002 [IMG]http://i122.photobucket.com/albums/o254/bigedp51/7-17-201055522PM.jpg[/IMG] [IMG]http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054719PM.jpg[/IMG] [IMG]http://i122.photobucket.com/albums/o254/bigedp51/7-17-201054345PM.jpg[/IMG] [/QUOTE]
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case head seperation?
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