To me, it seems that JB's method of measuring case capacity, using water and placing a bullet in a fired case, makes a lot more sense than to the brim.
If, for example, one took the 26 Nosler case and necked it up to various larger calibers, the to the brim measurements would vary a lot more than the actual powder capacity would vary.
Now, if all case capacity measurement methods were on the same page....
DF
