An article and book chapter on the following subject were already on my "to do" list when someone on some forum asked a question about burning rates that begged for this discussion of bulk density. Then that *&^%$#@! stroke erased a bit of my memory, so even if I could remember which forum, I couldn't answer his question specifically. I don't remember what was confusing him. I do remember generally that none of the ensuing posts in the thread answered his question accurately.<P>Differences in bulk densities account for the fact that while x grains of powder A fills a case, x grains of powder B (same brand!) may either overflow the mouth or fail to fill the case. It's easy and common to think that a grain of one powder occupies the same space as a grain of any other powder -- that that a cubic inch of one powder weighs the same as a cubic inch of another powder. Ain't so, McGee!<P>To illustrate the different bulk densities of different powders, I planned to put equal charges of different powders in identical graduated cylinders, to report the differences in their bulk densities in an easily visualized set of figures.<P>This afternoon, I struggled across the yard to bring a canister of powder in from the garage. Wasn't sure but thought I might have some Winchester 231 or 296. Turned out I have both. When I set out a canister of each, side by side, the dramatic difference in their diameters and heights was striking. I checked their net weights -- one pound (453.6 grams) each.<P>I had my illustration for showing the difference in the bulk densities of two Ball powders from the same manufacturer!<P>The cylindrical main body of the one-pound W-W 296 canister is about 2.6 inches in diameter and about 6 inches high.<P>The cylindrical main body of the one-pound W-W 231 canister is about 3.4 inches in diameter and about 7.2 inches high.<P>Quick, rough figgerin' suggests that one pound (7,000 grains) of W-W 296 occupies about 30 cubic inches, and a pound of W-W 231 occupies about 65 cubic inches. The same ratio applies to any other weight of these two powders, of course.
