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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
New Oehler 35P, New skyscreen rail, First Test Data
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<blockquote data-quote="Pdvdh" data-source="post: 433512" data-attributes="member: 4191"><p>When I use the term '<em>delta of the differences</em>', I am meaning '<em>paralleled each other</em>'. That's the true reflection of the precision and repeatability of the chronograph setups. In other words, if I were to reset my skyscreen separation distances such that two units provided basically the same velocity (never being sure which velocity is closer to the true actual velocity), and then fired a string of bullets over the chronographs, the maximum difference between the recorded velocities is generally less than 5 fps.</p><p></p><p>As to determining which velocity of the four recorded velocities I receive from my chronograph setup is closest to the true bullet velocity (the most accurate - closest to the bullseye)? I rely on the three chronographed velocities from the units with the skyscreens with the largest separation distance. I measure and set the skyscreen separation distance as accurately as possible, and then look at the recorded velocities from the three units. In my initial test run using the new skyscreen rail, the two Oehlers with their 6' separation distance and the PACT with its 56" separation distance, were all in very close agreement. So I would average the three velocities, cross my fingers, and conclude that the average of the three is very close to the true bullet velocity. I don't know of any better way to go about it with the tools at my disposal. I don't claim to be able to know the absolute true velocity of my loads. I do claim to be able to determine the ES and SD of my loads to a very high level of accuracy <u>and</u> precision. And my gut feeling is the true bullet velocity isn't very far from the average of the three units.</p><p></p><p>It would be nice to transport my three units down to Oehler's factory and run them concurrently with one of their $15,000 units, or run them next to a radar set-up. Other than that, averaging the recorded velocity over multiple units is the best idea I've been able to come up with - so that's what I do.</p><p></p><p>Running multiple chronographs concurrently allows one to quantitatively identify the more reliable chronograph system from the less reliable chronograph system. I keep a running record of all of my shot strings on my PC. This is the process that allows me to state that my Oehler 33 is a more reliable unit with its Skyscreen IIIs - in fading light - than my PACT. Neither the Oehler 33 or the PACT are the current offerings from those two companies. In good lighting, the PACT operates just about as well as the Oehler 33. But I give the Oehler 33 the edge in performance because over the long haul, the ES produced by the Oehler 33 is generally 2-3 fps less than the ES recorded by the PACT. To me, this means the precision of the Oehler 33 is slightly better than the precision coming out of the PACT.</p><p></p><p>I haven't shot over the Oehler 35P other than the once - and I've posted that date in my initial Post. But over time, I will learn how it compares - performance wise - to the Oehler 33 and PACT.</p><p></p><p>Paul</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 433512, member: 4191"] When I use the term '[I]delta of the differences[/I]', I am meaning '[I]paralleled each other[/I]'. That's the true reflection of the precision and repeatability of the chronograph setups. In other words, if I were to reset my skyscreen separation distances such that two units provided basically the same velocity (never being sure which velocity is closer to the true actual velocity), and then fired a string of bullets over the chronographs, the maximum difference between the recorded velocities is generally less than 5 fps. As to determining which velocity of the four recorded velocities I receive from my chronograph setup is closest to the true bullet velocity (the most accurate - closest to the bullseye)? I rely on the three chronographed velocities from the units with the skyscreens with the largest separation distance. I measure and set the skyscreen separation distance as accurately as possible, and then look at the recorded velocities from the three units. In my initial test run using the new skyscreen rail, the two Oehlers with their 6' separation distance and the PACT with its 56" separation distance, were all in very close agreement. So I would average the three velocities, cross my fingers, and conclude that the average of the three is very close to the true bullet velocity. I don't know of any better way to go about it with the tools at my disposal. I don't claim to be able to know the absolute true velocity of my loads. I do claim to be able to determine the ES and SD of my loads to a very high level of accuracy [U]and[/U] precision. And my gut feeling is the true bullet velocity isn't very far from the average of the three units. It would be nice to transport my three units down to Oehler's factory and run them concurrently with one of their $15,000 units, or run them next to a radar set-up. Other than that, averaging the recorded velocity over multiple units is the best idea I've been able to come up with - so that's what I do. Running multiple chronographs concurrently allows one to quantitatively identify the more reliable chronograph system from the less reliable chronograph system. I keep a running record of all of my shot strings on my PC. This is the process that allows me to state that my Oehler 33 is a more reliable unit with its Skyscreen IIIs - in fading light - than my PACT. Neither the Oehler 33 or the PACT are the current offerings from those two companies. In good lighting, the PACT operates just about as well as the Oehler 33. But I give the Oehler 33 the edge in performance because over the long haul, the ES produced by the Oehler 33 is generally 2-3 fps less than the ES recorded by the PACT. To me, this means the precision of the Oehler 33 is slightly better than the precision coming out of the PACT. I haven't shot over the Oehler 35P other than the once - and I've posted that date in my initial Post. But over time, I will learn how it compares - performance wise - to the Oehler 33 and PACT. Paul [/QUOTE]
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New Oehler 35P, New skyscreen rail, First Test Data
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