Weight difference between brass

[Robinhood]

you need to weigh your brass with water in the cases to actually know if the weight will effect performance...the actual weight of the case don't matter its the case capacity that makes the difference.

This has been proven to be somewhat true over and over again. However one has to question if brass is trimmed to length, flash holes debburred and all external dimensions being very similar(i would assume post sizing), where can the extra weight reside in the heavier cases?

I wanted to go to the trouble of sorting cases by weighing the water, after ten I found the difference to be astounding on cases with the same dry weight. I had noticed in my reloading infancy that when trimming cases some had to be sized with a small base die just to get them to protrude enough for the Wilson cutter to remove brass and not cut steel. By default the Wilson case trimmer holder I used allows you to determine how much spring back that your case body has after sizing. Here is an example.

[edited;(I was using a 308 and 223 wilson case holder not this WSSM version)]

After some time I started to sort my cases after trimming and sizing first, by weight secondly then by how far the slid into my Wilson case trimming body. This is not my photo but what I experienced after full length sizing, I had some that protruded considerably out of the small end and some did not extend enough to trim. The ones that came up short were remedied by using a small base die. I noticed that when I sorted cases that weighed the same and fit into my holder the same depth that water weights were within the tenth's of grains. So in my opinion when someone goes about sorting cases by weight, if your external dimensions are very similar, case weight is relevant. MHO. Thoughts?