I always sort a batch of new brass by weight. The heaviest 10/20% are relegated to plinking loads, rarely used. The lightest 10% are for hunting. The remainder are for load development and general shooting. Sometimes the difference between lightest and heaviest isn’t great enough to pay it any attention but we don’t know till we weigh them. Buying cases in large lots simplifies things. Sorting cases simply by weight and not taking into consideration case design by different manufactures could be misleading. Dissimilarities will show up on the chronograph. But, we don’t need to go that far before dissimilarities become evident. Throwing weight out the window, all we’re looking for is case volume. The only time weight matters is when measuring a large number of cases from the same lot. There are a couple of ways to measure volume and can be found on the internet, it’s slow and tedious. What I did, mostly for personal entertainment and to see if it actually showed results, was to use small grained ball powder. Fill a case slowly to overflowing utilizing a drop tube, scrape off the excess and weigh the case contents. Do the same case a few times to measure your margin of error and to stabilize your technique. Don’t attempt this till you have a lot of time to waste or have an actual purpose in mind. It will be interesting.......
A while back, I was acquiring brass for which there was no source, I had to make it. The closest thing to what I wanted was the 6.5 Creedmoor since it is nothing more than a slightly blown out .250 Savage with a longer neck. I’d have been better off using the 6mm but didn’t figure that out till later. Anyhow, after acquiring several different makes of 6.5 Creedmoor and running them through the .250 die and trimming all the necks to the same length, there was so little weight difference between them, it didn’t matter. Like I mentioned earlier, it’s about case volume. When doing all this weighing stuff I did find two cases much heavier that the average of the same mfg/lot. When doing the volume check, I included these two cases and they proved to have less volume.
A very simple way to overcome all this procedural stuff is to be precise in your powder measuring and filling your cases with a long drop tube and slow pouring of the powder into the case. If a particular case has a powder level higher or lower than average, it should probably be discarded into its proper group. High volume vs low volume.
One thing I learned is, the larger the case, the greater the difference will be. Another thing, small volume cases will deliver close to the same velocity as high volume cases as long as the powder level in the case is the same. Less but close.
If your ultimate goal is accuracy, small volume cases might be best. “Might.” If velocity for hunting ammo is most important, high volume cases will deliver.