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Rifles, Reloading, Optics, Equipment
Reloading
Case head separation
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<blockquote data-quote="bigedp51" data-source="post: 1294526" data-attributes="member: 28965"><p>If you have a Hornady cartridge case headspace gauge you measure the fired case and adjust the die for minimum shoulder bump.</p><p></p><p>Reloading dies and chambers vary in diameter and headspace length. And setting up the die per the dies instructions can over resize the case.</p><p></p><p>When you bump the shoulder back .002 when sizing, the chambered cartridge will have .002 head clearance. The further you push the shoulder back the more head clearance you create and the further the case can stretch when fired.</p><p></p><p> <img src="http://i.imgur.com/HK76WCp.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>The reason they say to only bump the shoulder back .001 to .002 is this is within the elastic limits of the brass and the case should not stretch and thin.</p><p></p><p>Below if the die is not adjusted low enough the case can end up longer than the chamber at the blue dotted line.</p><p></p><p>When the die is properly adjusted the shoulder will be pushed/bumped .001 to .002 below the red dotted line.</p><p></p><p>When the die is adjusted per the dies instructions it can excessively push the case shoulder back and create excessive head clearance. This excessive head clearance allows the case to stretch and thin in the base web area when fired.</p><p></p><p>Example, I have a Lee .223 die when setup per the instructions and making hard contact with the shell holder. The die will push the case shoulder back .009 shorter than a GO gauge and create .010 to .011 head clearance. This same die will reduce the case diameter "more" than a small base die will.</p><p></p><p>Bottom line, your dies can be adjusted for a custom fit to your chamber and not over resize the case.</p><p></p><p><img src="http://i.imgur.com/wm05ArY.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="bigedp51, post: 1294526, member: 28965"] If you have a Hornady cartridge case headspace gauge you measure the fired case and adjust the die for minimum shoulder bump. Reloading dies and chambers vary in diameter and headspace length. And setting up the die per the dies instructions can over resize the case. When you bump the shoulder back .002 when sizing, the chambered cartridge will have .002 head clearance. The further you push the shoulder back the more head clearance you create and the further the case can stretch when fired. [IMG]http://i.imgur.com/HK76WCp.jpg[/IMG] The reason they say to only bump the shoulder back .001 to .002 is this is within the elastic limits of the brass and the case should not stretch and thin. Below if the die is not adjusted low enough the case can end up longer than the chamber at the blue dotted line. When the die is properly adjusted the shoulder will be pushed/bumped .001 to .002 below the red dotted line. When the die is adjusted per the dies instructions it can excessively push the case shoulder back and create excessive head clearance. This excessive head clearance allows the case to stretch and thin in the base web area when fired. Example, I have a Lee .223 die when setup per the instructions and making hard contact with the shell holder. The die will push the case shoulder back .009 shorter than a GO gauge and create .010 to .011 head clearance. This same die will reduce the case diameter "more" than a small base die will. Bottom line, your dies can be adjusted for a custom fit to your chamber and not over resize the case. [IMG]http://i.imgur.com/wm05ArY.gif[/IMG] [/QUOTE]
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Reloading
Case head separation
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