It’s a good question. I think the problem here is that there are some unsubstantiated assumptions.
Let’s just say you start out with two pieces of brass disc of exactly the same weight and two cases are extruded. Now when you fire the case and FLR, length trim, chamfer and deburr and all the other stuff, what is to guarantee that the internal diameters are exactly the same?
For example, the head area with the rim and primer pocket etc, they don’t contribute to internal volume but use up brass, if they are not exactly the same shape and volume, they will affect the brass which makes up the wall and neck and thus internal volume.
This is all theoretical since I have never measure case volume, but I can see why there could be reasons why equal weight does not always equal volume…
Let’s just say you start out with two pieces of brass disc of exactly the same weight and two cases are extruded. Now when you fire the case and FLR, length trim, chamfer and deburr and all the other stuff, what is to guarantee that the internal diameters are exactly the same?
For example, the head area with the rim and primer pocket etc, they don’t contribute to internal volume but use up brass, if they are not exactly the same shape and volume, they will affect the brass which makes up the wall and neck and thus internal volume.
This is all theoretical since I have never measure case volume, but I can see why there could be reasons why equal weight does not always equal volume…
