Thread: Case capacity question.

No doubt the forum autostuff has offered you this thread, where they discuss it but I don't think it quite answers your question.

Case capacity, measured in mL is used to compare different cartridges eg 308 vs 3006.
Within a batch from the same manufacturer, cases are often sorted by grain weight, to remove outliers and designate a set or two with very similar volumes. The best time to do this is before they are first fired because powder deposits build up weight and over time as you trim, chamfer and ream pockets each case needs a different treatment and the 5th firing weight won't reflect the amount of brass originally in the walls and base. I don't know why brass varies so much in how much needs to be trimmed after just a few firings.