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Rifles, Reloading, Optics, Equipment
Reloading
Case weight variability question
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<blockquote data-quote="QuietTexan" data-source="post: 2192641" data-attributes="member: 116181"><p>Radial growth down the length of the case body would have more impact on volume than the shoulder alone. There is a lot more case from the web to the shoulder than just the shoulder that moves forward. The shoulder of a .308 is 0.152" long, the rest of the case body is 1.4082" from the head to the shoulder, that's almost 10x more length, and the shoulder is a truncated cone so it's 30-40% less volume than a comparable cylinder anyways. Your load is 10FPS faster in the second-fired case because the body growth added 10-15x more volume from a .0005" radial increase that didn't have to be expanded on the second shot compared to the lost volume from shoulder having been forward an extra .0010" or whatever your measurement was for the initial shot and being set back some by the die. </p><p></p><p>I'm trying to say (poorly probably) that I think there is a whole lot more volume in the cylindrical case body at play here than in the truncated cone of the shoulder of the case, so a smaller increase in the case body radius is more impactful than the shoulder moving, even if in absolute terms the shoulder is moving 2-3x further forward than the case body is outward.</p><p></p><p>Bryan Litz would probably be crying from laughing so hard if he read me trying to explain my thoughts on this... it'd be like Bear Grylls watching a Cro-Magnon make a fire by beating rocks together. Hopefully endearing and not pitiful.</p></blockquote><p></p>
[QUOTE="QuietTexan, post: 2192641, member: 116181"] Radial growth down the length of the case body would have more impact on volume than the shoulder alone. There is a lot more case from the web to the shoulder than just the shoulder that moves forward. The shoulder of a .308 is 0.152" long, the rest of the case body is 1.4082" from the head to the shoulder, that's almost 10x more length, and the shoulder is a truncated cone so it's 30-40% less volume than a comparable cylinder anyways. Your load is 10FPS faster in the second-fired case because the body growth added 10-15x more volume from a .0005" radial increase that didn't have to be expanded on the second shot compared to the lost volume from shoulder having been forward an extra .0010" or whatever your measurement was for the initial shot and being set back some by the die. I'm trying to say (poorly probably) that I think there is a whole lot more volume in the cylindrical case body at play here than in the truncated cone of the shoulder of the case, so a smaller increase in the case body radius is more impactful than the shoulder moving, even if in absolute terms the shoulder is moving 2-3x further forward than the case body is outward. Bryan Litz would probably be crying from laughing so hard if he read me trying to explain my thoughts on this... it'd be like Bear Grylls watching a Cro-Magnon make a fire by beating rocks together. Hopefully endearing and not pitiful. [/QUOTE]
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Case weight variability question
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