Home Forums Hunting & Shooting Hunter's Campfire Beyond burning rates

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.

ken, glad to hear you are up and about. now lets get down to the brass tack here. The answer to the question is which weighs more a pound of lead or a pound of feathers. I usually lean towards the lead [img]images/icons/wink.gif" border="0[/img] Yeah I know they weigh the same, it's that darn liberal arts education poking it's nasty head up again. But the volume of the two is considerably different. Take fire wood for example there are many species of trees some not at all dence such as cotton wood and others so dence they will not float on water such as ebony. The potential available energy in each type of wood is proportinate to it's density as woods are are similar. However gun powder is a different fish alltogether. Being a man made the stored energy is dependant on it's make up. Take 4227 it comes in 1/2 pounds while most others come in pound cans. Staying with IMR family you will find the that velocities generated from equal cartridges are not divided in half if the same weight of powder is used. Black powder is measured by volume rather than by weight because it's composistion is such as it is not a precise explosive. Alittle more or a little less makes little difference in power developed. Don't try that with Bulls Eye. What it comes down to is that we are playing with fire here and it is best to follow instructions.<P>Bullwnkl.

After the snow finally stopped falling (several winters back), two feet of it covered everything. I was chatting with the fellow across the street. He looked at the two feet of white above his roof line, then at the sun, and with some anxiety said, "I've got to get up there and shovel that off. Pretty soon, it's gonna start melting, and then it'll be HEAVY."<P>No, I didn't even try to enlighten him about the distinction between weight and density. For two days, I watched from warm, indoor ease as he shoveled snow off his roof.

The way I heard it -- from my dad when I was a wee lad -- the question was ...<BR>Which is heavier, a pound of gold or a pound of lead?<P>This isn't a trick question, as some folks automatically assume, but a didactic question to introduce a distinction. The answer is a pound of lead -- 16 ounces (avoirdupois) in a pound of lead to 12 ounces (troy or apothecary) in a pound of gold.<P>The two ounces aren't exactly the same weight, but they're close enough for any wee country lad (1 troy ounce = 1.0971429 avoirdupois ounce) -- a lot closer than 12 and 16.

Here's another way to look at the same relationships between the weights and the volumes of different powders -- their respective bulk densities.<P>I've just compiled a list of how many grains of each powder (105 powders, all told) would occupy the net capacity of a certain case (.220 Howell) with a certain bullet (75-grain Hornady A-Max) and an over-all loaded length of 3.00 inches -- the space occupied by a tad more than 56 grains of water.<P>The range is from 23.9 grains of the least-dense powder to 56.9 grains of the densest powder.<P>IOW, equal-size piles of powder x and powder y weigh 23.9 and 56.9 grains, respectively.