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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Experiment for quantifying lot to lot variations of powders
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<blockquote data-quote="Michael Courtney" data-source="post: 683244" data-attributes="member: 28191"><p>That's exactly my point. it's not about any offense. The point is that adding a pressure measurement approximately doubles the cost, time, effort, and expense of the experiment, but I don't see how it doubles the value of the results. </p><p></p><p>How do the (less accurate) pressure measurements make the determination of velocity variations more convincing? I can see how they might illuminate the underlying causes of any velocity variations that might be observed (pressure variations).</p><p></p><p></p><p></p><p>If the extra data added no time or expense, then I would agree, more data is better. But pressure measurements slow data acquisition by a factor of two or three, and the analysis is considerably more involved as well. You're talking about several hundred pressure curves. The system requires attaching a strain gage to a barrel with an adhesive. The calibration procedure is rather involved to ensure accurate results, and the whole procedure needs to be repeated for each rifle barrel in the study for even marginal accuracy. </p><p></p><p></p><p></p><p>Not really. If the velocity variations are smaller than 1%, how do we expect to see the reasons for it in pressure measurements that are only accurate to 3%? Theoretically, the velocity is proportional to the area under the pressure curve, but the pressure measurements are not accurate enough to correlate with velocity.</p></blockquote><p></p>
[QUOTE="Michael Courtney, post: 683244, member: 28191"] That's exactly my point. it's not about any offense. The point is that adding a pressure measurement approximately doubles the cost, time, effort, and expense of the experiment, but I don't see how it doubles the value of the results. How do the (less accurate) pressure measurements make the determination of velocity variations more convincing? I can see how they might illuminate the underlying causes of any velocity variations that might be observed (pressure variations). If the extra data added no time or expense, then I would agree, more data is better. But pressure measurements slow data acquisition by a factor of two or three, and the analysis is considerably more involved as well. You're talking about several hundred pressure curves. The system requires attaching a strain gage to a barrel with an adhesive. The calibration procedure is rather involved to ensure accurate results, and the whole procedure needs to be repeated for each rifle barrel in the study for even marginal accuracy. Not really. If the velocity variations are smaller than 1%, how do we expect to see the reasons for it in pressure measurements that are only accurate to 3%? Theoretically, the velocity is proportional to the area under the pressure curve, but the pressure measurements are not accurate enough to correlate with velocity. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Experiment for quantifying lot to lot variations of powders
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