I have never done any sorting of brass before but am interested in learning more about it as a method for increasing case uniformity.

I have two boxes of new Lapua 6BR cases with different mfg lot numbers on them. It was a slow night here so I weighed 25 pieces from each box with the following results;

Lot A
Average = 128.6 gr
STDEV = 0.35

Lot B
Average = 128.7 gr
STDEV = 0.51

My understanding is that it is a common practice to determine the average weight and then select all the cases that fall within +/- X and exclude all those that do not.

For the weights shown above, what is a reasonable tolerance to set for culling the outliers?

Thanks