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Rifles, Reloading, Optics, Equipment
Reloading
Nonsensical Headspace Measurements on 223rem cases...??
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<blockquote data-quote="twadsw01" data-source="post: 1386855" data-attributes="member: 24663"><p>Thanks for the help, guys.</p><p></p><p>I took some additional data in totally unprepped cases...</p><p></p><p>So, here is some additional data, which indicates that my initial measurements prompting this thread might have been erroneous in some way (maybe not zeroing out the mic, etc., etc.,?). I took twenty cases from totally unprepped through the reloading process, sans powder and primer. The purpose was to be able to see how individual cases were effected by each step in the process.</p><p></p><p>The same process as I normally employ for reloading was used, and I did not ensure the inside of the necks were lubricated (simply due to the fact that I wanted an apples-to-apples comparison with the cases I originally measured for this thread).</p><p></p><p>I will dump the raw numbers (screenshot form), and two box plots, showing length and headspace after each reloading step (where applicable - e.g., did/can not measure case length after a bullet has been seated).</p><p></p><p>In my opinion, nothing looks out-of-place here. Cases lengthen after sizing then the longer cases are indeed being trimmed while the shorter ones aren't touched by the trimmer - this is readily observed by the box plot, where it appears that simply the top of one box has been lopped off, leaving the bottom untouched. Also, unprepped cases starting with longer headspace get bumped by the sizing die, while shorter headspace cases do not, and none are being bumped back an undue amount, it seems (0.002" on average).</p><p></p><p> - Average case length comes out to 1.750", as desired.</p><p> - Average headspace is 1.462".</p><p> - Average case length growth from the sizing die is ~10/1000".</p><p> - As mentioned before, average shoulder setback is 2/1000".</p><p></p><p>There are still some high outliers in the headspace category, which could be explained by the spring back phenomenon, possibly.</p><p></p><p>Of note is that the one case that started with shorter headspace than where the sizing die was bumping all the shoulders back to - case 18, 1.461" unprepped headspace measurement - this case's headspace actually became longer in the sizing die, as expected because of the brass growing while being inserted in the die, but the shoulder never being setback by the die. Is this a concern? I.e., could this case the head of the case to become unduly weakened due to the brass never being 'crunched' back down at the end of the stroke?</p><p></p><p>Does anything look strange, unexpected, concerning about any of this?</p><p></p><p>Also, thank you, everyone, for all of the input into this thread. I appreciate it.</p><p></p><p></p><p><img src="https://i.imgur.com/gdbMdW3.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p><img src="https://i.imgur.com/2WCBeJ0.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="twadsw01, post: 1386855, member: 24663"] Thanks for the help, guys. I took some additional data in totally unprepped cases... So, here is some additional data, which indicates that my initial measurements prompting this thread might have been erroneous in some way (maybe not zeroing out the mic, etc., etc.,?). I took twenty cases from totally unprepped through the reloading process, sans powder and primer. The purpose was to be able to see how individual cases were effected by each step in the process. The same process as I normally employ for reloading was used, and I did not ensure the inside of the necks were lubricated (simply due to the fact that I wanted an apples-to-apples comparison with the cases I originally measured for this thread). I will dump the raw numbers (screenshot form), and two box plots, showing length and headspace after each reloading step (where applicable - e.g., did/can not measure case length after a bullet has been seated). In my opinion, nothing looks out-of-place here. Cases lengthen after sizing then the longer cases are indeed being trimmed while the shorter ones aren't touched by the trimmer - this is readily observed by the box plot, where it appears that simply the top of one box has been lopped off, leaving the bottom untouched. Also, unprepped cases starting with longer headspace get bumped by the sizing die, while shorter headspace cases do not, and none are being bumped back an undue amount, it seems (0.002" on average). - Average case length comes out to 1.750", as desired. - Average headspace is 1.462". - Average case length growth from the sizing die is ~10/1000". - As mentioned before, average shoulder setback is 2/1000". There are still some high outliers in the headspace category, which could be explained by the spring back phenomenon, possibly. Of note is that the one case that started with shorter headspace than where the sizing die was bumping all the shoulders back to - case 18, 1.461" unprepped headspace measurement - this case's headspace actually became longer in the sizing die, as expected because of the brass growing while being inserted in the die, but the shoulder never being setback by the die. Is this a concern? I.e., could this case the head of the case to become unduly weakened due to the brass never being 'crunched' back down at the end of the stroke? Does anything look strange, unexpected, concerning about any of this? Also, thank you, everyone, for all of the input into this thread. I appreciate it. [img]https://i.imgur.com/gdbMdW3.jpg[/img] [img]https://i.imgur.com/2WCBeJ0.jpg[/img] [/QUOTE]
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Nonsensical Headspace Measurements on 223rem cases...??
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