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Rifles, Reloading, Optics, Equipment
Reloading
ladder test? does it work
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<blockquote data-quote="CatShooter" data-source="post: 146428" data-attributes="member: 7"><p>I am not a supporter of this "theory", as it has too many flaws in it. Some say they have found good loads with it, but even a blind pig finds an acorn or two.</p><p></p><p>The "theory" is based on the idea that shooting errors are due to vibrations in the barrels, like a pendulum, and if you can find one end of the swing, the rifle will be more accurate, because minor variations in velocity will have less effect at one end of the sweep, than if the chosen load is in the middle of the sweep.</p><p></p><p>Sounds good on paper, but there are a lotta holes in it.</p><p></p><p>The first is that it assumes that barrel whip is the only cause of large groups... and that is NOT true.</p><p></p><p>If a load of powder "A" gives tiny groups at 3,200 fps... the same velocity with powder "B" might give humongous groups. So that fact right there kills the harmonic, or node theory. While thin barrels can show vibration patterns, they effect of the vibrations are often smaller that the size of the groups caused by other factors... and stable barrels of quality will often show small groups at many velocities, and each increase in powder will cause the group to climb up a bit, so you will have a string of small groups with each one a bit higher than the previous... and in the 5 or 10 groups, you may find one that is better... or maybe all with be so close that you pick the one that meets your needs.</p><p></p><p>But the real problem with ladders is this. With a average barrel that shoots (say) 1-1/4" groups, any shot can statistically fall in a circle of 1-1/4". If we increase the load by 1/2 grain, we have an increase in velocity, but any of the shots of the second load can fall into a circle 1-1/4" circle, (AND THE CIRCLES OVERLAP)... and so on for five variables with a load spread of 2.5 grains.</p><p></p><p>So with just these five load variables we can shoot a ladder. So, from the Point of aim:</p><p></p><p>The first shot can be 5/8" high, or 5/8" below the poi. </p><p>The "center" of the second shot will be a bit higher because of the increase in velocity, but from that new base, the second shot can be 5/8" high, or 5/8" below the "new center"... and so on.</p><p></p><p>Now... as velocity increases, the center on impact of a "group will be higher, but in that group, each individual shot can be 5/8" below, or 5/8" higher.</p><p></p><p>To bring this to a more logical example... if we took two of the cases that are 1/2 grain apart, and repeatedly shot the two, we would find that each pair would vare and the second shot could be either above or BELOW the first shot... and each pair would vary by as much as an inch.</p><p> </p><p>To make this make more sense now... take a bunch of cases that have been match prepped (weighed, etc). Break the bunch into groups of 5 cases, and then vary the load by 1/2 grain, so you wind up with five sets of five cases.</p><p></p><p>Now shoot the first five as a ladder on one target.</p><p>Then with a new target, do the same with the second group.</p><p>Then do the same with the other three sets.</p><p></p><p>When you wind up with is five targets with five "ladders".</p><p></p><p>Now... here's the killer. If you lay the targets out on a desk, none of the targets will resemble the others.</p><p></p><p>If you give the five targets to a "ladder believer", and tell him that they come from five different rifles, and ask him to "analyze" the targets, you will get five different "best loads" for the five targets... which says that there is no information in the ladders, because if there was, then a separate analysis of each target would give the same load as best, IF the ladder theory works.</p><p></p><p>Don't take my word for it... do it, and see for yourself. </p><p></p><p>.</p></blockquote><p></p>
[QUOTE="CatShooter, post: 146428, member: 7"] I am not a supporter of this "theory", as it has too many flaws in it. Some say they have found good loads with it, but even a blind pig finds an acorn or two. The "theory" is based on the idea that shooting errors are due to vibrations in the barrels, like a pendulum, and if you can find one end of the swing, the rifle will be more accurate, because minor variations in velocity will have less effect at one end of the sweep, than if the chosen load is in the middle of the sweep. Sounds good on paper, but there are a lotta holes in it. The first is that it assumes that barrel whip is the only cause of large groups... and that is NOT true. If a load of powder "A" gives tiny groups at 3,200 fps... the same velocity with powder "B" might give humongous groups. So that fact right there kills the harmonic, or node theory. While thin barrels can show vibration patterns, they effect of the vibrations are often smaller that the size of the groups caused by other factors... and stable barrels of quality will often show small groups at many velocities, and each increase in powder will cause the group to climb up a bit, so you will have a string of small groups with each one a bit higher than the previous... and in the 5 or 10 groups, you may find one that is better... or maybe all with be so close that you pick the one that meets your needs. But the real problem with ladders is this. With a average barrel that shoots (say) 1-1/4" groups, any shot can statistically fall in a circle of 1-1/4". If we increase the load by 1/2 grain, we have an increase in velocity, but any of the shots of the second load can fall into a circle 1-1/4" circle, (AND THE CIRCLES OVERLAP)... and so on for five variables with a load spread of 2.5 grains. So with just these five load variables we can shoot a ladder. So, from the Point of aim: The first shot can be 5/8" high, or 5/8" below the poi. The "center" of the second shot will be a bit higher because of the increase in velocity, but from that new base, the second shot can be 5/8" high, or 5/8" below the "new center"... and so on. Now... as velocity increases, the center on impact of a "group will be higher, but in that group, each individual shot can be 5/8" below, or 5/8" higher. To bring this to a more logical example... if we took two of the cases that are 1/2 grain apart, and repeatedly shot the two, we would find that each pair would vare and the second shot could be either above or BELOW the first shot... and each pair would vary by as much as an inch. To make this make more sense now... take a bunch of cases that have been match prepped (weighed, etc). Break the bunch into groups of 5 cases, and then vary the load by 1/2 grain, so you wind up with five sets of five cases. Now shoot the first five as a ladder on one target. Then with a new target, do the same with the second group. Then do the same with the other three sets. When you wind up with is five targets with five "ladders". Now... here's the killer. If you lay the targets out on a desk, none of the targets will resemble the others. If you give the five targets to a "ladder believer", and tell him that they come from five different rifles, and ask him to "analyze" the targets, you will get five different "best loads" for the five targets... which says that there is no information in the ladders, because if there was, then a separate analysis of each target would give the same load as best, IF the ladder theory works. Don't take my word for it... do it, and see for yourself. . [/QUOTE]
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