Amount of gases produced by amount of powder

[Tokarev]

I must be having a blond moment, as I know exactly there was a chart somewhere, just like the burn rate charts, that had how much gas is created when burning different powders. But where?

[jlchucker]

Your question makes me wonder--what does this data mean? How will it affect sought-after accuracy and velocity, in a measurable, practical sense? On the other hand, those on the political left would probably be glad to use such data for an environmentalist tool to grab either guns, ammunition or components. Not trying to start a fight here, just curious.

[Andy_P]

I have always understood that a pound of powder contained the same amount of energy (gas volume) regardless of its relative quickness. The only difference was in how quickly it expanded. That's why (when within their working pressure range), more of a slower powder produces higher MV's then less of a quicker powder.

[felix]

True in practice. The quantity of "N" and "O" elements all together in the formula will determine the potential energy. The ratio of these two elements will affect the quality of the burn, and so to be absolutely honest, the powders must have the "same" amount of nitroglycerin to be honestly "compared". No matter, the burn RATE overshadows everything in terms of value. ... felix

[405]

Agree with above responses. I remember looking at some thermodynamic chamber tests of powders a long time ago. Seems IIRC that there were only small differences in total energy released by same unit weights of different powders but it was the pressure curve data that was of significance. The very small total energy differences I think only showed when comparing single base, double base, ball, etc. The differences in total gas volumes corrected to "1 atmosphere pressure" produced among all the powders was not significantly different when compared to the differences in burn rate-response to pressure (pressure curve), etc.

[felix]

The ideal pressure curve will emulate a triangle, absolute pressure over time, such that the pressure begins and ends with a zero quantity. Where the apex of the triangle exists within the barrel is determined by the burn RATE, which for smokeless is determined by the instantaneous pressure, and, for black by the relative position of the granules amongst themselves. ... felix

[helg]

I may give the blond answer, but 30 grains of powder when burned completely produce 30 grains of gases. It is that simple.

A powder may be characterized by heat of explosion, vivacity (or burning rate) and the whole shape of the pressure curve in the closed bomb, specific impulse and other parameters.

http://www.chuckhawks.com/powder_cartridge_testing.htm

[Hickory]

I did this once.

I aquired 2 weather baloons once from a Army surplus store.
Had them around for a couple of years. Ended up with a pound of powder with no name or numbers on it.

Long story short. When the fuse lite the powder the baloon filled out bigger than I expected it would.
The heat generated inside the baloon took it into the air an floated aways off before it burst.

[Tokarev]

> I may give the blond answer, but 30 grains of powder when burned completely produce 30 grains of gases. It is that simple.

It's a kind of no **** sherlock answer that was circling my brain's convolutions for a while.
The thing is, I need the volume of those 30 grains at atmospheric pressure in cubic feet.
This of course has nothing to do with fast or slow powders, I just need values for several major brands like HS6, IMR4227, IMR4064, HP38, H335.

[felix]

It appears you already have the available answer, or the means to obtain the answer the way you need it. I thought the balloon trick was quite ingenious. ... felix

[Tokarev]

If I did the baloon test at the range, the boys would not just kick me out - they would make me laughing stock for generations to come.

Doesn't 308 produce some 300 cubic feet of gas? I think by now I tried everything in Google which is a combination of 'gas' and 'powder' :(

If I wasn't mathematically challenged, I could have calculated the volume from case volume and max pressure. Like this:
Volume of 308 case is 3.43434223 grams of water. Max pressure is 4219 atmospheres.
That means that 512 cubic feet of gases can be produced by firing a 308 loaded to the maximum.
I was not too far off with 300. Anyway, that basically means that 44-46 grains of 4064 produce somewhere between 400 and 500 cubic feet of gas. Nice?