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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Custom action pressure ceiling.
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<blockquote data-quote="Fitch" data-source="post: 375136" data-attributes="member: 19372"><p>+2. I'm right there with ya. There is no magic. Physics isn't negotiable. Reality is independent of the observer, at least with Newtonian mechanics which is what we are dealing with. </p><p> </p><p>The problem with pushing the limits is that there is no practical way to know what limits are being pushed and how hard they are being pushed. To an experienced test engineer, like myself, the whole reloading and internal ballistic process is remarkably devoid of measured feedback related to stress and pressure. There is no reliable measurement of anything that says what might be the weak link in the pressure containment boundry. Even test barrels had huge unknown errors for decades because the testers didn't understand what the CUP system was actually measuring. Even now the instrumentation has errors that aren't always accounted for. </p><p> </p><p>Sometimes it's the brass, sometimes it isn't. When it isn't the brass there are no pressure signs at all but it can still let go. </p><p> </p><p>The various action parts look undamaged right up until they let go on the next round. The stresses don't show, but they are there. Static pressures aren't necessarily the determinant - the dymamics of how stresses are applied can make a big difference - fatigue failure becomes a real possibility. Operating outside the design limits with no data is a prescription for disaster. </p><p> </p><p>There have been some spectacular examples of what can happen when that is done. The fact that one is operating outside the design envelope and nothing has broken so far is not an indication of any sort that the system has more capability than was deisgned into it, or that it won't break on the next round. The Challenger disaster comes to mind as a spectacular example but folks don't seem to learn from it. The principles are the same in reloading, just the scale is different.</p><p> </p><p>The difference between proof testing and normal design maximum pressures isn't margin met to be used for covering testosterone spills by those awash in the "right stuff" at the reloading bench - it's margin intended to cover the uncertainties and imponderables associated with pressure containment - material defects, tolerance variations, stress intensification blemishes like sharp scratches in a critical location, and so on. It isn't available to use for safely getting more velocity. </p><p> </p><p>There is a lot of merit to staying in the designed limits of the cartridge specifications. There is no rational basis for intentionally exceeding them in the name of a flatter trajectory or gaining another few feet per second. None.</p><p> </p><p>Fitch</p></blockquote><p></p>
[QUOTE="Fitch, post: 375136, member: 19372"] +2. I'm right there with ya. There is no magic. Physics isn't negotiable. Reality is independent of the observer, at least with Newtonian mechanics which is what we are dealing with. The problem with pushing the limits is that there is no practical way to know what limits are being pushed and how hard they are being pushed. To an experienced test engineer, like myself, the whole reloading and internal ballistic process is remarkably devoid of measured feedback related to stress and pressure. There is no reliable measurement of anything that says what might be the weak link in the pressure containment boundry. Even test barrels had huge unknown errors for decades because the testers didn't understand what the CUP system was actually measuring. Even now the instrumentation has errors that aren't always accounted for. Sometimes it's the brass, sometimes it isn't. When it isn't the brass there are no pressure signs at all but it can still let go. The various action parts look undamaged right up until they let go on the next round. The stresses don't show, but they are there. Static pressures aren't necessarily the determinant - the dymamics of how stresses are applied can make a big difference - fatigue failure becomes a real possibility. Operating outside the design limits with no data is a prescription for disaster. There have been some spectacular examples of what can happen when that is done. The fact that one is operating outside the design envelope and nothing has broken so far is not an indication of any sort that the system has more capability than was deisgned into it, or that it won't break on the next round. The Challenger disaster comes to mind as a spectacular example but folks don't seem to learn from it. The principles are the same in reloading, just the scale is different. The difference between proof testing and normal design maximum pressures isn't margin met to be used for covering testosterone spills by those awash in the "right stuff" at the reloading bench - it's margin intended to cover the uncertainties and imponderables associated with pressure containment - material defects, tolerance variations, stress intensification blemishes like sharp scratches in a critical location, and so on. It isn't available to use for safely getting more velocity. There is a lot of merit to staying in the designed limits of the cartridge specifications. There is no rational basis for intentionally exceeding them in the name of a flatter trajectory or gaining another few feet per second. None. Fitch [/QUOTE]
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