I spent several weeks last winter organizing, sorting, decapping and tumbling my brass stash. I have read so many threads like this one that I decided to weigh some 223/5.56 cases. I picked 100 cases from several headstamps and fully prepped them to load. That is, I resized them, trimmed them, uniformed the bottom of the primer pocket, deburred the flash hole, swaged any primer crimps and tumbled them. Then I weighed them.
GFL WCC16 Lapua BHA Match Winchester LC-12 FC(crimped) Perfecta Aguila PPU WCC-02 RP
Average weight 97.8 94.0 92.9 94.1 93.4 92.4 92.6 97.1 95.7 95.1 92.4 91.6
Heaviest 98.0 95.2 93.5 95.6 94.7 93.4 93.7 97.9 97.3 97.0 93.6 93.2
Lightest 96.3 92.9 92.6 93.3 92.5 91.5 91.7 96.2 94.6 93.8 91.0 90.5
A few notes on my procedures;
1.I felt that trimming the cases and prepping the primer pockets gave me a better idea of the end product.
2. These were random lots of 100 each, not hand picked, although I culled any with serious dents or road rash.
3. Cases were trimmed with A Giraud trimmer and test have shown that I usually maintain lengths to within .001.
4. Cases were weighed on a RCBS ChargeMaster.
5. The same resizing die and same case prep tools were used on all cases and by the same person (Me).
6. I did not measure the variation in neck wall thickness.
7. I did not cull any numbers once the 100 cases were prepped and weighed.
The test that I have done on other calibers showed that the heavier cases held less liquid (alcohol) by weight than the lighter cases. I did not weigh the liquid capacity of any of these. We should assume that other lots of the same headstamp may be different than these. I understand that 100 is a small sample and also that any real mathematicians here may be able to improve on my methods. Hope some of you find this interesting! Cabin fever can be either a good or bad thing!
Edit to add, the site scrambled my spread sheet for some reason. I had the numbers lined up much neater under the headstamps. Oh well!