Ned Ludd
Silver $$ Contributor
In my hands, various Berger bullets (.224" and .308") have far less BTO variance than OAL variance. Thus, nose length variance makes up the lion's share of OAL variance in a given Lot# of bullets. I sort bullets by OAL for the purpose of pointing them. A single length group has a total of .0015" OAL variance within it, which means I can point all the bullets from a single length group without altering the pointing die micrometer setting.
If you were to use a similar approach with bullets sorted by BTO, I would start by centering the middle length group on the 0.4930 (#6) group, then work to either side in increments of .0015" or .002" to accommodate the rest of the bullets with BTO measurements farther from the median/average. The more important question I would ask regarding this approach is what is the minimal BTO variance for which you can actually shoot a difference? The answer to that might change the total number of sorted BTO length groups you will actually need into which to divide these bullets. I usually end up with 7 or 8 length groups from a typical Lot# of Bergers. There will usually be a small number of "extreme" outliers in the shortest and longest length group, that go outside the .0015" range of that particular length group, so I always re-sort those two groups before use. Otherwise, I'd probably need at least another couple length groups to cover the entire range, and the shortest/longest of those might only have a few bullets in each.
With bullets sorted by OAL, I always start load development with one of the middle groups. Obviously, there are usually more bullets per group near the middle of the overall range in a typical Gaussian distribution. For that reason, I tend to load for matches only from the middle 2 to 4 groups, leaving those farther away in length from the median for sighters/foulers, and practice.
If you were to use a similar approach with bullets sorted by BTO, I would start by centering the middle length group on the 0.4930 (#6) group, then work to either side in increments of .0015" or .002" to accommodate the rest of the bullets with BTO measurements farther from the median/average. The more important question I would ask regarding this approach is what is the minimal BTO variance for which you can actually shoot a difference? The answer to that might change the total number of sorted BTO length groups you will actually need into which to divide these bullets. I usually end up with 7 or 8 length groups from a typical Lot# of Bergers. There will usually be a small number of "extreme" outliers in the shortest and longest length group, that go outside the .0015" range of that particular length group, so I always re-sort those two groups before use. Otherwise, I'd probably need at least another couple length groups to cover the entire range, and the shortest/longest of those might only have a few bullets in each.
With bullets sorted by OAL, I always start load development with one of the middle groups. Obviously, there are usually more bullets per group near the middle of the overall range in a typical Gaussian distribution. For that reason, I tend to load for matches only from the middle 2 to 4 groups, leaving those farther away in length from the median for sighters/foulers, and practice.
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