Sorry to take so long to get back. Internet access from my current location is spotty, and my schedule is not my own.
Regarding case capacity: We need it in the fired condition. Just weigh it empty, then fill with water and weigh again. The difference in grains is the number we need. We also need the length of the same case, without any trimming or sizing between measuring the water capacity and measuring the length. It might pay to do a few and see how much difference there is.
To get an accurate capacity measurement, you need to get the water into the case without bubbles. I use an eyedropper. And, you should to get the surface of the water across the case mouth flat. I ue the eyedropper to add or subtract a little water until a reflection of a bright object with a straight edge (for instance, a window or a flourescent tube) looks straight instead of bowed. I can repeat a capacity measurement to 0.1 grain with that technique. But, capacities of even the same lot of fired cases will probably vary by more than 0.1 grain. And, cases from different manufacturers can vary in capacity by a few grains.