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Rifles, Reloading, Optics, Equipment
Reloading
Known Loads too hot now..why
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<blockquote data-quote="Pdvdh" data-source="post: 384969" data-attributes="member: 4191"><p>dodgefan,</p><p></p><p>Thanks for locating and providing us with that link. The article is directly applicable to the subject matter at hand. I'll pat myself on the back as my engineering intuition led to the same theoretical cause & effect findings as resulted from Varmint Al's computer modeling. </p><p></p><p>I took a graduate level Finite Element Method engineering course at Michigan State Univerity my last year of attendence. It's a high-tech method of mathematical modeling with tremendous value for applied engineering design. It had already acheived "state of the art" recognition as an engineering design tool with the auto and farm machinery manufacturers. It's so mathematically intensive and analytically exhaustive that it can't really be emplyed without computers. And our computers back in 1978 were slow clunkers compared to today. It's a specialized enough method of mathematical analysis that one wouldn't remain proficient unless working with it on a frequent and sustained basis. I've visited Varmint Al's website before. He's describes his background and he was employed in a field of work that resulted in extensive exposure to the use of Finite Element and Finite Differences analysis and modeling methods, as well as supportive computer software. He's probably come up with a pretty realistic projection of case head thrust versus case to chamber wall coefficients of expansion.</p><p></p><p>Varmint Al modeled about a 700 lb difference (~15% increase) in case head thrust between a rough chamber and a polished chamber. Most of us would probably experience a somewhat smaller percentage increase in case head thrust moving from a dry cartridge/chamber to a wet cartridge/chamber surface. That's more or less what I expected and that's why I committed myself to the position that a wet cartridge/chamber was a nonsensical explanation for the brass flow and stiff bolt lifts as reported by clhman, Buffalobob, and 300remum. </p><p></p><p>Varmint Al's modeling of case head thrust versus differing friction coefficients more or less confirms the position that if a wet case/chamber produces sufficiently increased case head thrust, so as to result in brass flow and stiff bolt lift, that our loads are probably already exceeding maximum pressure loads as published in the available reloading manuals. Get the internal cartridge pressures high enough to approach brass flow conditions with a dry case/chamber, and the added case head thrust allowed by the wet case/chamber could provide just enough case head to bolt face contact pressure to result in brass flow into the voids of the bolt face.</p><p></p><p>Enough!</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 384969, member: 4191"] dodgefan, Thanks for locating and providing us with that link. The article is directly applicable to the subject matter at hand. I'll pat myself on the back as my engineering intuition led to the same theoretical cause & effect findings as resulted from Varmint Al's computer modeling. I took a graduate level Finite Element Method engineering course at Michigan State Univerity my last year of attendence. It's a high-tech method of mathematical modeling with tremendous value for applied engineering design. It had already acheived "state of the art" recognition as an engineering design tool with the auto and farm machinery manufacturers. It's so mathematically intensive and analytically exhaustive that it can't really be emplyed without computers. And our computers back in 1978 were slow clunkers compared to today. It's a specialized enough method of mathematical analysis that one wouldn't remain proficient unless working with it on a frequent and sustained basis. I've visited Varmint Al's website before. He's describes his background and he was employed in a field of work that resulted in extensive exposure to the use of Finite Element and Finite Differences analysis and modeling methods, as well as supportive computer software. He's probably come up with a pretty realistic projection of case head thrust versus case to chamber wall coefficients of expansion. Varmint Al modeled about a 700 lb difference (~15% increase) in case head thrust between a rough chamber and a polished chamber. Most of us would probably experience a somewhat smaller percentage increase in case head thrust moving from a dry cartridge/chamber to a wet cartridge/chamber surface. That's more or less what I expected and that's why I committed myself to the position that a wet cartridge/chamber was a nonsensical explanation for the brass flow and stiff bolt lifts as reported by clhman, Buffalobob, and 300remum. Varmint Al's modeling of case head thrust versus differing friction coefficients more or less confirms the position that if a wet case/chamber produces sufficiently increased case head thrust, so as to result in brass flow and stiff bolt lift, that our loads are probably already exceeding maximum pressure loads as published in the available reloading manuals. Get the internal cartridge pressures high enough to approach brass flow conditions with a dry case/chamber, and the added case head thrust allowed by the wet case/chamber could provide just enough case head to bolt face contact pressure to result in brass flow into the voids of the bolt face. Enough! [/QUOTE]
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