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Rifles, Reloading, Optics, Equipment
Reloading
300wm rl26 help with pressure signs
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<blockquote data-quote="Pdvdh" data-source="post: 1122319" data-attributes="member: 4191"><p>We don't need to measure to 0.0001" case head expansion in order to identify excess pressure. So I don't need a 0.0001" scaled measuring device. If you think a 0.0001" scaled device is required to measure changes exceeding 0.0005", you must be selling measuring devices. </p><p></p><p>"<em>...<strong>in no manual does it state to use calipers of any type to measure case head expansion.</strong></em>" That statement doesn't mean anything. You advocate stiff bolt lift as a superior means of elevated pressure identification. I'm not aware of any manual that instructs to measure the force required to lift the bolt off a fired cartridge either. </p><p></p><p>No reloading manual tells us to exceed their published maximum load. Yet how many exceed those published maximum loads? No reloading manual tells us to change any of the components in their publish load recipes. Yet how many change out primers or casings? </p><p></p><p>I have no idea why you're focusing on the importance of knowing exact pressure values in psi. I never claimed cartridge belt/head expansion measurements can provide one with the numeric value of that fired cartridge's pressure. I never claimed a chronographed MV can be used to identify a numeric value of pressure. And I never stated I was measuring case belt/head expansion in an effort to obtain a numeric value for the magnitude of the pressure. We don't need a numeric pressure value to identify powder loads that expand case belts/heads. We can identify pressures that reach levels sufficient to expand case belts/heads by taking a simple measurement of case belt/head expansion. That's all I'm doing. Nothing magical. And it's all that's necessary to identify pressures that will render brass casings useless thru repetitive firings at those powder charges. </p><p></p><p>You recommend stiff bolt lift for high pressure identification. Does stiff bolt lift provide an "<strong>exact correlation to the pressure the cartridge is producing</strong>"? Obviously not. That doesn't mean that stiff bolt lift doesn't provide notice that the pressures may be excessive in a rifle. </p><p></p><p>You were wrong on two counts. </p><p>1) You wrongly stated "<strong>case expansion has no correlation to pressure, whatsoever.</strong>"</p><p>2) You stated "<strong>You cannot measure case head expansion ACCURATELY with calipers. You can ONLY measure case head expansion with a blade type micrometer that reads to .0001" accuracy.</strong>" Nowhere in this Thread did anyone identify the need to measure to 0.0001" - other than you. I confidently measure distances greater or equal to 0.0005" with my 0.001" calipers all the time. Others do also when +/-0.0001" is close enough. Even +/- 0.0002" is good enough.</p><p></p><p>For all your focus and effort stressing that "<strong>You can ONLY measure case head expansion with a blade type micrometer that reads to .0001" accuracy.</strong>" you then state that case head expansion is "<strong>not a good way to gauge pressure</strong>". So really, how important can it be to use a measuring instrument with 0.0001" markings to measure case head expansion to 0.0001" for purposes of identifying pressure? That's too funny. </p><p></p><p>All the OP desired was help with cartridge pressure signs. He wasn't striving to become a machinist or identify pressure levels to a numeric value +/- 50psi. He received help, and all ended well, partly by measuring case belt expansion with his <span style="font-size: 9px">unsuitable</span> <span style="font-size: 12px">0.001"</span> Mitutoyo caliper. He's not even a machinist. And I'm comforted knowing others can also measure what needs measured with a set of quality <span style="font-size: 12px">0.001"</span> calipers.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1122319, member: 4191"] We don't need to measure to 0.0001" case head expansion in order to identify excess pressure. So I don't need a 0.0001" scaled measuring device. If you think a 0.0001" scaled device is required to measure changes exceeding 0.0005", you must be selling measuring devices. "[I]...[B]in no manual does it state to use calipers of any type to measure case head expansion.[/B][/I]" That statement doesn't mean anything. You advocate stiff bolt lift as a superior means of elevated pressure identification. I'm not aware of any manual that instructs to measure the force required to lift the bolt off a fired cartridge either. No reloading manual tells us to exceed their published maximum load. Yet how many exceed those published maximum loads? No reloading manual tells us to change any of the components in their publish load recipes. Yet how many change out primers or casings? I have no idea why you're focusing on the importance of knowing exact pressure values in psi. I never claimed cartridge belt/head expansion measurements can provide one with the numeric value of that fired cartridge's pressure. I never claimed a chronographed MV can be used to identify a numeric value of pressure. And I never stated I was measuring case belt/head expansion in an effort to obtain a numeric value for the magnitude of the pressure. We don't need a numeric pressure value to identify powder loads that expand case belts/heads. We can identify pressures that reach levels sufficient to expand case belts/heads by taking a simple measurement of case belt/head expansion. That's all I'm doing. Nothing magical. And it's all that's necessary to identify pressures that will render brass casings useless thru repetitive firings at those powder charges. You recommend stiff bolt lift for high pressure identification. Does stiff bolt lift provide an "[B]exact correlation to the pressure the cartridge is producing[/B]"? Obviously not. That doesn't mean that stiff bolt lift doesn't provide notice that the pressures may be excessive in a rifle. You were wrong on two counts. 1) You wrongly stated "[B]case expansion has no correlation to pressure, whatsoever.[/B]" 2) You stated "[B]You cannot measure case head expansion ACCURATELY with calipers. You can ONLY measure case head expansion with a blade type micrometer that reads to .0001" accuracy.[/B]" Nowhere in this Thread did anyone identify the need to measure to 0.0001" - other than you. I confidently measure distances greater or equal to 0.0005" with my 0.001" calipers all the time. Others do also when +/-0.0001" is close enough. Even +/- 0.0002" is good enough. For all your focus and effort stressing that "[B]You can ONLY measure case head expansion with a blade type micrometer that reads to .0001" accuracy.[/B]" you then state that case head expansion is "[B]not a good way to gauge pressure[/B]". So really, how important can it be to use a measuring instrument with 0.0001" markings to measure case head expansion to 0.0001" for purposes of identifying pressure? That's too funny. All the OP desired was help with cartridge pressure signs. He wasn't striving to become a machinist or identify pressure levels to a numeric value +/- 50psi. He received help, and all ended well, partly by measuring case belt expansion with his [SIZE="1"]unsuitable[/SIZE] [SIZE="3"]0.001"[/SIZE] Mitutoyo caliper. He's not even a machinist. And I'm comforted knowing others can also measure what needs measured with a set of quality [SIZE="3"]0.001"[/SIZE] calipers. [/QUOTE]
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300wm rl26 help with pressure signs
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