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Rifles, Reloading, Optics, Equipment
Reloading
weighing brass
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<blockquote data-quote="Moosetracker" data-source="post: 304910" data-attributes="member: 5152"><p>I weight at least 30 once fired cases for each lot of brass I use in order to measure internal volume and enter the average volume represented by grains of H2O in Quickload. I've done this for hundreds of cases of different brands and calibers. Every time I do this I enter the data in an Excel spreadsheet and compare weights and internal volumes. I select the brass on the basis of 1% (+ or - 0.5% from the mean) variation of internal volume. My data shows that the correlation between weight and internal volume is valid less than 50% of the time. With Lapua brass the correlation is valid about 48% of the time. With Winchester brass it's less than 30%. </p><p></p><p>In my initial sampling of 30 cases, if I find 1 case with a variance of more than + or - 0.5%, I measure the internal volume of all the cases in the lot and weed out those that exceed the tolerance level. In my 338 Edge I've had Remington cases that vary as much as 10 grs and yet had practically the same internal volume. On the other hand I've had cases with similar weight where some where rejected for exceeding the internal volume tolerance. </p><p></p><p>I weight cases because I have to in order to measure internal volume. However, I'm absolutely convinced that selecting cases on the basis of weight alone is an absolute waste of time. In fact, to the extent that cases are selected by weight that should be rejected for exceeding internal volume tolerances, that practice is a potential source of vertical dispersion in long range shooting.</p></blockquote><p></p>
[QUOTE="Moosetracker, post: 304910, member: 5152"] I weight at least 30 once fired cases for each lot of brass I use in order to measure internal volume and enter the average volume represented by grains of H2O in Quickload. I've done this for hundreds of cases of different brands and calibers. Every time I do this I enter the data in an Excel spreadsheet and compare weights and internal volumes. I select the brass on the basis of 1% (+ or - 0.5% from the mean) variation of internal volume. My data shows that the correlation between weight and internal volume is valid less than 50% of the time. With Lapua brass the correlation is valid about 48% of the time. With Winchester brass it's less than 30%. In my initial sampling of 30 cases, if I find 1 case with a variance of more than + or - 0.5%, I measure the internal volume of all the cases in the lot and weed out those that exceed the tolerance level. In my 338 Edge I've had Remington cases that vary as much as 10 grs and yet had practically the same internal volume. On the other hand I've had cases with similar weight where some where rejected for exceeding the internal volume tolerance. I weight cases because I have to in order to measure internal volume. However, I'm absolutely convinced that selecting cases on the basis of weight alone is an absolute waste of time. In fact, to the extent that cases are selected by weight that should be rejected for exceeding internal volume tolerances, that practice is a potential source of vertical dispersion in long range shooting. [/QUOTE]
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Reloading
weighing brass
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