I would doubt there is much capacity difference in the cases you weighed, assuming they were the same trim length and all had primers in or all removed. In the most extreme case weight difference I have observed, there was a significant delta in capacity. That instance was 7mm Weatherby brass. Hornady weighed 243 gr and Weatherby weighed 212 gr. Hornady was less volume and produced pressure signs with less powder. I learned to carefully check case weight/capacity after that even between same brands of cases. Federal and Remington brass seems to be close in some cartridges, Winchester often lighter/more volume. Your experience may vary. Happy Trails
