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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
7mm Allen Mag test rifle finished.....
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<blockquote data-quote="ricka0" data-source="post: 76303" data-attributes="member: 3086"><p><strong>Re: wc872 burn rate</strong></p><p></p><p>[ QUOTE ]</p><p> <font color="purple"> You are correct Jon A. I work in science and occasionally search the literature for references and patents in these areas. There are some fairly sophisticated internal ballistics codes that have come out. They do not rely on the ideal gas law. Even low pressure Helium doesn't strictly obey the ideal gas law. Accurate modelling of any REAL gas is much more complicated. You should load your cartridge with Magnesium-Teflon-Viton (MTV) and then see if you believe in hotter powders!</font> </p><p></p><p>[/ QUOTE ]</p><p></p><p>Great. Provide a citation or explanation for what creates pressure in burning powder besides heat. I've already shown the other alternative <strong>n</strong> is insignificant.</p><p></p><p>You are correct in that gases deviate from the IGL - but it is a good approximation and as the chemists have stated - [*]powders are primarily differentiated by burn rate - not reactants. [*]Different powders deviate from the IGL in a very consistent fashion </p><p>For all the naysayers of the simple heat pump approximation - please provide an explanation rather than a summary dismissal.</p><p></p><p>Even some reproducible data with a thermocouple and chrono (controlling for ambient temp.) would be helpful. But simply saying I shot my gun with H-50BMG powder a few weeks ago then wc872 yesterday and the barrel was hotter with H-50BMG shows nothing. How much hotter? What was the shot rate? Ambient temp? Unless you control and measure these factors you only have the impetus to do so, but cannot come to any conclusion.</p><p></p><p>There are other factors which can explain throat erosion. How abrasive are the powders? Some powders are far more abrasive than others. This is especially important before the bullet forms a gas seal.</p><p></p><p>This does give me a good idea. Perhaps I can video my 50 BMGs at night (which have a jynormous flame) and see if I can figure out how much unburnt powder remains when the bullet exits.</p><p></p><p>The reason I'm so familar with bullet acceleration being so well approximated by <strong>PV=nRT</strong> is my extensive discussions with some chemists in my quest for a multi-stage powder that can flatten the pressure curve. I'm not the first to think of this idea.</p></blockquote><p></p>
[QUOTE="ricka0, post: 76303, member: 3086"] [b]Re: wc872 burn rate[/b] [ QUOTE ] <font color="purple"> You are correct Jon A. I work in science and occasionally search the literature for references and patents in these areas. There are some fairly sophisticated internal ballistics codes that have come out. They do not rely on the ideal gas law. Even low pressure Helium doesn't strictly obey the ideal gas law. Accurate modelling of any REAL gas is much more complicated. You should load your cartridge with Magnesium-Teflon-Viton (MTV) and then see if you believe in hotter powders!</font> [/ QUOTE ] Great. Provide a citation or explanation for what creates pressure in burning powder besides heat. I've already shown the other alternative [b]n[/b] is insignificant. You are correct in that gases deviate from the IGL - but it is a good approximation and as the chemists have stated - [*]powders are primarily differentiated by burn rate - not reactants. [*]Different powders deviate from the IGL in a very consistent fashion For all the naysayers of the simple heat pump approximation - please provide an explanation rather than a summary dismissal. Even some reproducible data with a thermocouple and chrono (controlling for ambient temp.) would be helpful. But simply saying I shot my gun with H-50BMG powder a few weeks ago then wc872 yesterday and the barrel was hotter with H-50BMG shows nothing. How much hotter? What was the shot rate? Ambient temp? Unless you control and measure these factors you only have the impetus to do so, but cannot come to any conclusion. There are other factors which can explain throat erosion. How abrasive are the powders? Some powders are far more abrasive than others. This is especially important before the bullet forms a gas seal. This does give me a good idea. Perhaps I can video my 50 BMGs at night (which have a jynormous flame) and see if I can figure out how much unburnt powder remains when the bullet exits. The reason I'm so familar with bullet acceleration being so well approximated by [b]PV=nRT[/b] is my extensive discussions with some chemists in my quest for a multi-stage powder that can flatten the pressure curve. I'm not the first to think of this idea. [/QUOTE]
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