1 oz = 16 drams, so a dram is a weight. There are 7,000 grains to a lb, 437.5 to an oz & 27.3438 to a dram. In practise a dram was usually measured by volume by both manufactures & home loaders of ammunition. The same can be equally said of modern day grains of smokeless.
I realize there are variations, but a chart I have somewhere, lists density of FFG Black as .94 thus a 1 dram charge should have the volume of 29 grains water. This works out to about .115 CuIn (Note above industry standard for a black powder measure).
