Depending on the brass manufacturer weights of cases can very quite a bit between manufacturers. So weighing cases to determine over all count is miss leading unless you know the weight of each manufacturer.
I have kept track of the case weights I use by manufacturer. So when fully loaded I add the case weight + projectile weight + powder weight minus the ammo can weight. So measuring a fully loaded round is very accurate. I also use this to calculate amount of rounds. Based on this I have been with in 1-2 rounds when calculating total rounds in an ammo can.
I think you may have quoted the wrong post.