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Rifles, Reloading, Optics, Equipment
Reloading
Case seperation during fire forming
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<blockquote data-quote="bigedp51" data-source="post: 1184196" data-attributes="member: 28965"><p>Normally the softer annealed upper part of the case will conform to the shape of the chamber as below. If you were forming cases from a longer case and the new shoulder was below the original annealed section the brass could be harder and brittle. Normally a case with too much headspace is pushed forward by the ejector until it contcasts the shoulder of the chamber. If the case is extremely short the case is pushed forward until the rim contracts the lip of the extractor. And this creates excessive head clearance between the rear of the case and the bolt face. And it is the rear of the case that stretches and separates when this happens. </p><p></p><p>If you look at the center case in the photo below you can see the primer protruding. The amount the primer is protruding is the actual head clearance or the "air space" between the rear of the case and the bolt face. Meaning forward movement of the case was stopped by the extractor and the soft upper shoulder and neck section conformed to the chamber. And the case did not separate because military cases are thicker or harder than commercial cases in the base of the case. </p><p></p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/762-30-06_zps36671c81.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/762nato3006_zps0c005d4c.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>I don't know anything about the 7mm Sherman short mag, but I learned a great deal about excess headspace as a 18 year old in the military. And excess headspace is mainly created in dimly lit bars by unscrupulous bartenders who know under age drinkers can't complain to the management.</p><p></p><p><img src="http://i122.photobucket.com/albums/o254/bigedp51/excessheadspace_zpsf2634b56.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="bigedp51, post: 1184196, member: 28965"] Normally the softer annealed upper part of the case will conform to the shape of the chamber as below. If you were forming cases from a longer case and the new shoulder was below the original annealed section the brass could be harder and brittle. Normally a case with too much headspace is pushed forward by the ejector until it contcasts the shoulder of the chamber. If the case is extremely short the case is pushed forward until the rim contracts the lip of the extractor. And this creates excessive head clearance between the rear of the case and the bolt face. And it is the rear of the case that stretches and separates when this happens. If you look at the center case in the photo below you can see the primer protruding. The amount the primer is protruding is the actual head clearance or the "air space" between the rear of the case and the bolt face. Meaning forward movement of the case was stopped by the extractor and the soft upper shoulder and neck section conformed to the chamber. And the case did not separate because military cases are thicker or harder than commercial cases in the base of the case. [IMG]http://i122.photobucket.com/albums/o254/bigedp51/762-30-06_zps36671c81.jpg[/IMG] [IMG]http://i122.photobucket.com/albums/o254/bigedp51/762nato3006_zps0c005d4c.jpg[/IMG] I don't know anything about the 7mm Sherman short mag, but I learned a great deal about excess headspace as a 18 year old in the military. And excess headspace is mainly created in dimly lit bars by unscrupulous bartenders who know under age drinkers can't complain to the management. [IMG]http://i122.photobucket.com/albums/o254/bigedp51/excessheadspace_zpsf2634b56.jpg[/IMG] [/QUOTE]
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Reloading
Case seperation during fire forming
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