When you measure water capacity, do it with a case that has been fired in YOUR gun and has NOT been resized. Leave the spent primer in so that the water doesn't leak out. Weigh the empty case. Then, fill it with water so that it is FLUSH across the mouth and weigh it again. The difference is the case capacity in "grains of water" which is the standard of measure in the U.S.
To get the water flush across the case mouth, use an eye dropper to fill the case and over-fill it a little at first, so that the edges of the case mouth get wetted. Then use the eye dropper to suck just a little water back out of the case so that the water surface across the mouth is flat. You can use a reflection of a light with a straight edge, like a window of florescent bulb, to check for a flat water surface; when the reflection is also straight, then the water surface is flat instead of bowed in or out.
It is easiest to weigh the long rifle cases on an electonic scale. On a balance beam scale, the pan hanger gets in the way of keeping the case upright. If all you have is a balance beam scale, then you can easily make a special hanger for weighing your cases when they are filled with water. Just take a piece of stiff wire, like maybe 14 gauge electrical wire (stripped) and twist it in a loose spiral around a dowel that is somewhat larger in diameter than your case. On one end, bend the wire so that it goes straight along the dowel instead of spiraling, then when the dowel is removed, bend that part of the wires so that it becomes a hanger that clears the case easily but ends-up with a hook that attaches to the loop on the end of your balance beam. On the other end, bend a short piece of the wire directly across the end of the spiral to serve as the "bottom" of your basket. To keep this shell basket from hitting the table that the scale is sitting on, place the scale near the edge of the table and let the basket hang over the side.
SL1
