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Rifles, Reloading, Optics, Equipment
Reloading
Load Development Help/Opinions
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<blockquote data-quote="RegionRat" data-source="post: 2863972" data-attributes="member: 57231"><p>There is way to much noise in terms of group centroid shift in the test.</p><p>There is either an issue with the bench technique, or the rifle doesn't like the recipe, or both.</p><p></p><p>Any variation on the OCW Method is aimed at a study of the group centroid. The goal is to see if there are at least a few charge steps where the centroid is stable and/or to at least avoid the steps where there is a rapid shift. On your test, you can hardly find any group centroid stability because the size of the groups and their variations are too large.</p><p></p><p>As often as not, in an OCW test we don't know anything about the group stats till after follow up tests of the best charge steps found in the first pass. Those follow up tests are the time to explore seating depth and to gather velocity stats and here is also where the user should consider distance testing.</p><p></p><p>Also, if we have set a goal that is reasonable, we have to learn when to punt or when to try harder on a recipe. That takes some skill, experience, and objectivity.</p><p></p><p>Small sample tests that study a chronograph are a problem in our sport. These chronograph dominated tests are very misleading when the context is a carry rifle and the sample sizes are too small.</p><p></p><p>When the context is a sporting carry gun, the challenge is the weight of the rifle and the recoil. Shooting a big cartridge in a light gun sets the stage for the potential accuracy, especially if the driver doesn't understand the discipline to control recoil reaction with extreme NPA and follow through. If the rig's reaction is allowed to vary, it is hopeless. </p><p></p><p>The Christensen Arms Mesa is called a featherlight in their adds and is roughly 6.5 lbs, which makes it very easy to carry up and down the mountains, but also makes it very difficult to shoot well. Set your distance and goals accordingly would be my advice.</p><p></p><p>That recoil, if left unmanaged by shooting technique, will dominate the target performance. </p><p></p><p>At the maximum range for a carry gun, the group study should take priority and the resulting velocity stats will follow. This metaphor will shift only slightly with a heavy barrel LR match gun or an ELR rig, but in fact the shot fall performance will only be good with excellent ammo workmanship and that is what determine those velocity stats in that context, and only after group testing selects the best recipe to begin with.</p><p></p><p>By definition, if the groups at distance are good, then so are the velocity stats. And, great velocity stats that sit on a scatter node are cold comfort. Don't fixate on velocity stats too early in the search or at short range. Those variations on what was called the Satterlee Method and so called "flat spots" evaporate when more samples are filled in.</p><p></p><p>The signal-to-noise challenge in load development is a real problem. Light rifles using heavy cartridges will emphasize the bench technique as the major contributor to shot dispersion. If the recoil isn't managed, your noise will be so large you can never see the secondary harmonics.</p></blockquote><p></p>
[QUOTE="RegionRat, post: 2863972, member: 57231"] There is way to much noise in terms of group centroid shift in the test. There is either an issue with the bench technique, or the rifle doesn't like the recipe, or both. Any variation on the OCW Method is aimed at a study of the group centroid. The goal is to see if there are at least a few charge steps where the centroid is stable and/or to at least avoid the steps where there is a rapid shift. On your test, you can hardly find any group centroid stability because the size of the groups and their variations are too large. As often as not, in an OCW test we don't know anything about the group stats till after follow up tests of the best charge steps found in the first pass. Those follow up tests are the time to explore seating depth and to gather velocity stats and here is also where the user should consider distance testing. Also, if we have set a goal that is reasonable, we have to learn when to punt or when to try harder on a recipe. That takes some skill, experience, and objectivity. Small sample tests that study a chronograph are a problem in our sport. These chronograph dominated tests are very misleading when the context is a carry rifle and the sample sizes are too small. When the context is a sporting carry gun, the challenge is the weight of the rifle and the recoil. Shooting a big cartridge in a light gun sets the stage for the potential accuracy, especially if the driver doesn't understand the discipline to control recoil reaction with extreme NPA and follow through. If the rig's reaction is allowed to vary, it is hopeless. The Christensen Arms Mesa is called a featherlight in their adds and is roughly 6.5 lbs, which makes it very easy to carry up and down the mountains, but also makes it very difficult to shoot well. Set your distance and goals accordingly would be my advice. That recoil, if left unmanaged by shooting technique, will dominate the target performance. At the maximum range for a carry gun, the group study should take priority and the resulting velocity stats will follow. This metaphor will shift only slightly with a heavy barrel LR match gun or an ELR rig, but in fact the shot fall performance will only be good with excellent ammo workmanship and that is what determine those velocity stats in that context, and only after group testing selects the best recipe to begin with. By definition, if the groups at distance are good, then so are the velocity stats. And, great velocity stats that sit on a scatter node are cold comfort. Don't fixate on velocity stats too early in the search or at short range. Those variations on what was called the Satterlee Method and so called "flat spots" evaporate when more samples are filled in. The signal-to-noise challenge in load development is a real problem. Light rifles using heavy cartridges will emphasize the bench technique as the major contributor to shot dispersion. If the recoil isn't managed, your noise will be so large you can never see the secondary harmonics. [/QUOTE]
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