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Rifles, Reloading, Optics, Equipment
Reloading
Reading pressure. Great article about it
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<blockquote data-quote="Mikecr" data-source="post: 1611479" data-attributes="member: 1521"><p>Before powder development I use culled cases to do a test for 'MyMax'. I incrementally go up in load, measuring each extracted case at it's webline (widest expansion) with a blade mic. I usually see this diameter go up to a plateau and hold while continuing. At some point there is a yielding step change at this datum. Diameter amplitudes are different with smaller/larger cartridges of course, but the step change from plateau is the point where FL sizing would have to be included in reloading cycles.</p><p></p><p>That's brass yielding into the chamber's own expansion, where you would hope the brass would spring back more than the chamber(for easy extraction). But once brass reaches yielding it takes smaller force increases to continue that yielding.</p><p>You feel that just prior to twisting the head off a bolt, and Ya know it's coming..</p><p>Continued use at that MyMax pressure, without counter-sizing, will lead to popping extraction. It can even with sizing, or it could be cleared enough with case lube or with lapping out the breech mouth a bit.</p><p></p><p>What I've noticed with MY cartridges & chambers, is that this yield point consistently calcs out very near SAAMI max in QuickLoad. Given this, I suspect there is some connection there, at xxKpsi pressure, when max it's <em>actually</em> determined by SAAMI.[ATTACH=full]129411[/ATTACH]</p></blockquote><p></p>
[QUOTE="Mikecr, post: 1611479, member: 1521"] Before powder development I use culled cases to do a test for 'MyMax'. I incrementally go up in load, measuring each extracted case at it's webline (widest expansion) with a blade mic. I usually see this diameter go up to a plateau and hold while continuing. At some point there is a yielding step change at this datum. Diameter amplitudes are different with smaller/larger cartridges of course, but the step change from plateau is the point where FL sizing would have to be included in reloading cycles. That's brass yielding into the chamber's own expansion, where you would hope the brass would spring back more than the chamber(for easy extraction). But once brass reaches yielding it takes smaller force increases to continue that yielding. You feel that just prior to twisting the head off a bolt, and Ya know it's coming.. Continued use at that MyMax pressure, without counter-sizing, will lead to popping extraction. It can even with sizing, or it could be cleared enough with case lube or with lapping out the breech mouth a bit. What I've noticed with MY cartridges & chambers, is that this yield point consistently calcs out very near SAAMI max in QuickLoad. Given this, I suspect there is some connection there, at xxKpsi pressure, when max it's [I]actually[/I] determined by SAAMI.[ATTACH=full]129411[/ATTACH] [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Reading pressure. Great article about it
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