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Rifles, Reloading, Optics, Equipment
Reloading
Accuracy or low ES?
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<blockquote data-quote="KYpatriot" data-source="post: 1042522" data-attributes="member: 48028"><p>Ridgerunner and dkhunter have said it best but my two cents is....you dont know much about the true accuracy or velocity of a load with a single 5 shot group. The difference in drop at the range you will be shooting represents your maximum accuracy potential and should be easy to determine, so if you are happy with it then load devlopment is done. I cant really imagine being happy with 100 fps ES for 1000 yard shooting though unless i was shooting at some large targets. </p><p></p><p>By the way shot dispersion is NOT linear. It varies with time of flight, not distance. A 1 inch group at 100 yards does not mean 10 inches at 1000 yards. Rather, you take the time of flight to 1000, divide it by the time of flight to 100, and myltiply that by the group size at 100. </p><p></p><p>For example lets say you are shooting a 308 winchester at 100 yards. Accuracy is consistent at .75 inches, time of flight is 0.115 sec. At 1000 yards in the same conditions, time of flight would be 1.713 sec. What would we expect the group size to be with this load at 1000? It would be (tof@1000 / tof@100) * group size at 100. In this case (1.713/0.115) * 0.75 = 11.17inches, not the 7.5 inches As commonly thought. From this we see that instead of group size increasing by a factor of ten like we would expect, it is closer to 14 for this load. Better bc and higher velocity can bring this down, but it will always be more than the ratio of the target ranges because it is the ratio of times of flight that really count.</p></blockquote><p></p>
[QUOTE="KYpatriot, post: 1042522, member: 48028"] Ridgerunner and dkhunter have said it best but my two cents is....you dont know much about the true accuracy or velocity of a load with a single 5 shot group. The difference in drop at the range you will be shooting represents your maximum accuracy potential and should be easy to determine, so if you are happy with it then load devlopment is done. I cant really imagine being happy with 100 fps ES for 1000 yard shooting though unless i was shooting at some large targets. By the way shot dispersion is NOT linear. It varies with time of flight, not distance. A 1 inch group at 100 yards does not mean 10 inches at 1000 yards. Rather, you take the time of flight to 1000, divide it by the time of flight to 100, and myltiply that by the group size at 100. For example lets say you are shooting a 308 winchester at 100 yards. Accuracy is consistent at .75 inches, time of flight is 0.115 sec. At 1000 yards in the same conditions, time of flight would be 1.713 sec. What would we expect the group size to be with this load at 1000? It would be (tof@1000 / tof@100) * group size at 100. In this case (1.713/0.115) * 0.75 = 11.17inches, not the 7.5 inches As commonly thought. From this we see that instead of group size increasing by a factor of ten like we would expect, it is closer to 14 for this load. Better bc and higher velocity can bring this down, but it will always be more than the ratio of the target ranges because it is the ratio of times of flight that really count. [/QUOTE]
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Accuracy or low ES?
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