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Rifles, Reloading, Optics, Equipment
Reloading
Newbie needs advice
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<blockquote data-quote="RegionRat" data-source="post: 2657020" data-attributes="member: 57231"><p>When you said you ran a ladder and saw nodes, can you be more specific?</p><p></p><p>What distance was the test run? </p><p></p><p>Did shots cluster (vertically)?</p><p></p><p>Unfortunately, the word "ladder" has been used for many different things and has become ambiguous over the last 20 years. What it used to mean was a test run out at a significant distance, using charge steps to observe the composite vertical shotfall harmonics. The test required distance to expose vertical speed issues as well as harmonic issues. </p><p></p><p>Any non-linear clusters of shots were then investigated with follow-up group testing and seating depth testing. The benefit of the Audette Ladder test method was to expose the composite of the structural harmonics and internal ballistics harmonics (speed stats) to find the better nodes to further investigate.</p><p></p><p>If your "ladder" was run too close, then the velocity spreads do not show vertical, and the structural harmonics will also be too difficult to sort.</p><p></p><p>If you can only tune at short distances, the better methods are closer to OCW and look for point of impact shifts. However, if the groups are huge compared to any shifts, due to the arrow or the Indian, then the results are muddy.</p><p></p><p>You already mentioned it, but it is worth repeating... that there isn't a point to doing velocity stats on three or five shot samples. Even the group size study is subject to the same problem, where you can get a factor of 2 bigger or smaller in the next trial if you are not lucky. </p><p></p><p>With respect to advice, I find myself often telling folks to take the chrono data for safety, but not to prioritize it unless the group nodes are identified first. </p><p></p><p>Many times, the best speed stats may not align with the best target performance. In a carry gun, structural harmonics are stronger than they are in match guns. Once in a while, the SD/ES is kind to you and aligns to the best target, but not always. Up close, you really don't need velocity stats at all. Speed stats do become important out past 600 yards, but they should only be used once the group nodes are found.</p><p></p><p>At distances where you are well down the trajectory, when you have good target/group performance, your speed stats are going to be at least decent otherwise your vertical spreads would be poor. The corollary is also true with a carry gun, great speed stats with bad groups is cold comfort.</p><p></p><p>With a carry profile bbl that is meant to go more than 400 yards when required, the Audette Ladder method can save you time and shot count. I would give it a try if you haven't already. It is difficult since you have to be aware of barrel heating, cleaning/fouling, and your own fatigue. But that is true of any shooting with a carry gun in a potent caliber.</p></blockquote><p></p>
[QUOTE="RegionRat, post: 2657020, member: 57231"] When you said you ran a ladder and saw nodes, can you be more specific? What distance was the test run? Did shots cluster (vertically)? Unfortunately, the word "ladder" has been used for many different things and has become ambiguous over the last 20 years. What it used to mean was a test run out at a significant distance, using charge steps to observe the composite vertical shotfall harmonics. The test required distance to expose vertical speed issues as well as harmonic issues. Any non-linear clusters of shots were then investigated with follow-up group testing and seating depth testing. The benefit of the Audette Ladder test method was to expose the composite of the structural harmonics and internal ballistics harmonics (speed stats) to find the better nodes to further investigate. If your "ladder" was run too close, then the velocity spreads do not show vertical, and the structural harmonics will also be too difficult to sort. If you can only tune at short distances, the better methods are closer to OCW and look for point of impact shifts. However, if the groups are huge compared to any shifts, due to the arrow or the Indian, then the results are muddy. You already mentioned it, but it is worth repeating... that there isn't a point to doing velocity stats on three or five shot samples. Even the group size study is subject to the same problem, where you can get a factor of 2 bigger or smaller in the next trial if you are not lucky. With respect to advice, I find myself often telling folks to take the chrono data for safety, but not to prioritize it unless the group nodes are identified first. Many times, the best speed stats may not align with the best target performance. In a carry gun, structural harmonics are stronger than they are in match guns. Once in a while, the SD/ES is kind to you and aligns to the best target, but not always. Up close, you really don't need velocity stats at all. Speed stats do become important out past 600 yards, but they should only be used once the group nodes are found. At distances where you are well down the trajectory, when you have good target/group performance, your speed stats are going to be at least decent otherwise your vertical spreads would be poor. The corollary is also true with a carry gun, great speed stats with bad groups is cold comfort. With a carry profile bbl that is meant to go more than 400 yards when required, the Audette Ladder method can save you time and shot count. I would give it a try if you haven't already. It is difficult since you have to be aware of barrel heating, cleaning/fouling, and your own fatigue. But that is true of any shooting with a carry gun in a potent caliber. [/QUOTE]
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