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Rifles, Reloading, Optics, Equipment
Reloading
Seating question
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<blockquote data-quote="QuietTexan" data-source="post: 2508813" data-attributes="member: 116181"><p>True in general, but have you every checked the consistency of one single insert? Measure the same exact bullet ten times with a Hornady vs a SAC. If the Hornady records a range on the same bullet..... you have to apply a tolerance spec to the CBTO measurement you get from it. It the range is 0.001", how can you say that a 0.001" variance in seating depth is real and not in the measuring tool? The measurement can't be more precise than the measuring system is capable of measuring accurately. A common mistake is that if the tool reads to 0.000xx" then the measurement is actually that precise. The measurement is only as accurate as the tool, false precision is the problem. The Hornady tool might only be precise to 0.002", and falsely precise measurements that vary by 0.001" are a finer resolution than the tool can accurately measure. The oblong hole can cant the bullet base, which results in an error that's the cosine of the angle induced by the hole being out of round.</p><p></p><p>Have you done it? I have, and the Hornady tool reads different on the same bullet in subsequent measurements <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite9" alt=":eek:" title="Eek! :eek:" loading="lazy" data-shortname=":eek:" /> Because there's a compounding error based on the roundness of the hole in the comparator. Put in bullet, rotate bullet, different measurements.</p><p></p><p>Have you ever compared two calipers against each other? Another interesting exercise, because of compounding linear error there also.</p><p></p><p>There's a difference in a $30 dial caliper with a Hornady insert and a $200 Mitu with a SAC insert - namely, repeatability.</p></blockquote><p></p>
[QUOTE="QuietTexan, post: 2508813, member: 116181"] True in general, but have you every checked the consistency of one single insert? Measure the same exact bullet ten times with a Hornady vs a SAC. If the Hornady records a range on the same bullet..... you have to apply a tolerance spec to the CBTO measurement you get from it. It the range is 0.001", how can you say that a 0.001" variance in seating depth is real and not in the measuring tool? The measurement can't be more precise than the measuring system is capable of measuring accurately. A common mistake is that if the tool reads to 0.000xx" then the measurement is actually that precise. The measurement is only as accurate as the tool, false precision is the problem. The Hornady tool might only be precise to 0.002", and falsely precise measurements that vary by 0.001" are a finer resolution than the tool can accurately measure. The oblong hole can cant the bullet base, which results in an error that's the cosine of the angle induced by the hole being out of round. Have you done it? I have, and the Hornady tool reads different on the same bullet in subsequent measurements :eek: Because there's a compounding error based on the roundness of the hole in the comparator. Put in bullet, rotate bullet, different measurements. Have you ever compared two calipers against each other? Another interesting exercise, because of compounding linear error there also. There's a difference in a $30 dial caliper with a Hornady insert and a $200 Mitu with a SAC insert - namely, repeatability. [/QUOTE]
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Seating question
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