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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Using Quick Load for Optimum Barrel Timing and OCW Node Matches
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<blockquote data-quote="Oak_Leaf" data-source="post: 3005520" data-attributes="member: 128477"><p>First, if my post sounded terse, I apologize. It wasn't really geared toward you, but more toward another reference whose text that you had copied. That reference made it sound like OBT and harmonics were the same phenomenon. It happens a lot, even on the other site <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> </p><p></p><p>But yes, you are correct in that Chris has the only reasonable way to come up with any kind of educated guess as to what barrel time might produce a sweet spot for the expansion/contraction modes. But, like another poster said, I too believe that the barrel bending mode is usually the dominate factor over the expansion/contraction of bore, even in heavy barrel rifles. And, I think it has been shown in the real world scenarios that nodes (bending cycle sweet spots) can be found in certain velocity ranges, for a given barrel length length. These velocities will likely correspond somewhat with a particular barrel time. Again, a loose correlation. But when you find those sweet spots through actual target ladder/ocw, then calibrate QL correctly to your velocities, then you could conceivably determine an actual barrel time that correlates with the bending modes. This barrel time can be somewhat portable over to a different load for that rifle. I have done that before on a several rifles changing powders, and even bullets, and believe it or not it works, but again the correlation is a little looser.</p><p></p><p>The problem I have with QL for this type of work is that I have never successfully calibrated it to my actual velocities and had that calibration hold up over any useful range of charges. There's the popular way of calibrating, using Burn Rate, Weighting Factor, etc., but it just doesn't hold up over a very wide charge range. My program inputs are all very exact too. I think the REAL calibration would involve getting into the other parameters of the powder, but I do not know enough about Julian's model to get into that yet. I have tried some things, and actually gotten it to track over a wide range, but I am pretty skeptical of what I had to do. This leaves me doubting any barrel time other than for the charge I specifically calibrated the velocity to - and honestly, I'm skeptical of that one too. At the end of the day, when I find a good load, what I'm seeing is the OBT, according to Chris's calculations, does not line up with the barrel time in QL for the charge, or charge range, that shoots the best. Again, I believe it is because the bending modes are the dominant. In my mind, that pretty much messes everything up for me because of the possibility that the OBT is getting masked by the bending modes, so true calibration of QL to Chris's predictions becomes almost impossible. Hope that makes sense.</p></blockquote><p></p>
[QUOTE="Oak_Leaf, post: 3005520, member: 128477"] First, if my post sounded terse, I apologize. It wasn't really geared toward you, but more toward another reference whose text that you had copied. That reference made it sound like OBT and harmonics were the same phenomenon. It happens a lot, even on the other site :) But yes, you are correct in that Chris has the only reasonable way to come up with any kind of educated guess as to what barrel time might produce a sweet spot for the expansion/contraction modes. But, like another poster said, I too believe that the barrel bending mode is usually the dominate factor over the expansion/contraction of bore, even in heavy barrel rifles. And, I think it has been shown in the real world scenarios that nodes (bending cycle sweet spots) can be found in certain velocity ranges, for a given barrel length length. These velocities will likely correspond somewhat with a particular barrel time. Again, a loose correlation. But when you find those sweet spots through actual target ladder/ocw, then calibrate QL correctly to your velocities, then you could conceivably determine an actual barrel time that correlates with the bending modes. This barrel time can be somewhat portable over to a different load for that rifle. I have done that before on a several rifles changing powders, and even bullets, and believe it or not it works, but again the correlation is a little looser. The problem I have with QL for this type of work is that I have never successfully calibrated it to my actual velocities and had that calibration hold up over any useful range of charges. There's the popular way of calibrating, using Burn Rate, Weighting Factor, etc., but it just doesn't hold up over a very wide charge range. My program inputs are all very exact too. I think the REAL calibration would involve getting into the other parameters of the powder, but I do not know enough about Julian's model to get into that yet. I have tried some things, and actually gotten it to track over a wide range, but I am pretty skeptical of what I had to do. This leaves me doubting any barrel time other than for the charge I specifically calibrated the velocity to - and honestly, I'm skeptical of that one too. At the end of the day, when I find a good load, what I'm seeing is the OBT, according to Chris's calculations, does not line up with the barrel time in QL for the charge, or charge range, that shoots the best. Again, I believe it is because the bending modes are the dominant. In my mind, that pretty much messes everything up for me because of the possibility that the OBT is getting masked by the bending modes, so true calibration of QL to Chris's predictions becomes almost impossible. Hope that makes sense. [/QUOTE]
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Using Quick Load for Optimum Barrel Timing and OCW Node Matches
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