Measure?

[Bullet]

Black powder is measured in grains of water – volume? So when the black powder data says 30grains, this means the volume of 30grains of water?

 

[oneshooter]

BP measures

Black powder is measured by weight. There are 7000grains to a pound. The measures simply measure a volume that is the same as the weight of the charge. Thus a 30 gr measure will throw a volume of powder that will weigh 30 grains.

Simple!

Oneshooter
Livin in Texas

 

[Duncaninfrance]

AND

I measure my BP in Grammes because that's what my Lyman scale is incremented in here. 1 gramme = 15.43 grains.

Just thought you would like to know

 

[mykeal]

OR

OR, you could use drams, as is sometimes done with fowlers. 1 dram = 27.34375 grains.

BUT, to put a fine point on what Oneshooter said: we do in fact use volume directly, not weight. The volume measure is designed such that it is equivalent to weight WHEN USING REAL BLACK POWDER. It is not equivalent when using substitute black powders, which tend to weigh less.

 

[Bullet]

I thought I read that black powder could not be measured by weight because it would vary do to the amount of moisture it absorbed, hence the volume measurement. But I thought the volume measurement was based on water weight – volume. I read so much that I can’t remember where I got this other than I wanted to find out if this is correct or not. Anyone know?

 

[Heinrich]

As a BP shot that has submitted myself to measuring by volume, remember that 40gr of FFFg and FFg is not the same. With smaller space between the particles of FFFg, due to smaller particle size of FFFg, your volume is more dense, therefore you have "more" powder packed into that volume.

Therefore, apart from faster combustion, you also have more powder to burn once loaded.

 

[Bad Flynch]

Well, we hav been to this before, but here it goes again.

We inherited an archaic system of measuring Black Powder. That system uses what amounts to a bulk specific gravity measurement. It arose in the days when BP was measured in the field. And that is: 40 volume grains of BP is the same volume as 40 grains, by weight, of water. That system arose in order to standardize a way to measure BP in the field. Can you imagine weighing out BP in the heat of battle, or weighing BP while trying to get a second shot at a deer?

It is not that we want to be perverse, but it is an established system that has been in use for hundreds of years. Modern shooters think that they will improve their accuracy and groups by weighing powder charges, but testing has not shown that to be so: the old system produces good shooting loads just as easily as the new system. That is apparently because BP loads have two qualities: BP is a low-energy propellant and changes in charges make relatively small changes in results and in addition, around 55% of a BP load remains unburned and exits the barrel before burning or just falling to the ground. That percentage changes a lot from shot-to-shot and from firearm-to-firearm, so one gets plenty of internal variation, even in a well-weighed load.

In case you are wondering, modern internal ballistic computer programs measure case capacity in grains of water, whether the data is intended for use with smokeless or BP. Weighing the capacity of cases is very much the easiest way to to that.

Relax about the volume grains system; it works quite well, in spite of modern technology.

 

[Bullet]

Bad Flynch

Thanks!

 

[DixieTexian]

As a BP shot that has submitted myself to measuring by volume, remember that 40gr of FFFg and FFg is not the same. With smaller space between the particles of FFFg, due to smaller particle size of FFFg, your volume is more dense, therefore you have "more" powder packed into that volume.

Therefore, apart from faster combustion, you also have more powder to burn once loaded

According to my soils professor, when I took the class, smaller particle size actually has more airspace than larger particle sizes. While the space between the particles is smaller, there are more of them, causing increased air space. He said if you feel a glass up with marbles, and another of the same size with bb's, the one with the bb's in it will actually hold more water than the one with marbles. Maybe, with finer grained powder, te increased surface area makes it more efficient at burning and causes it to burn hotter than larger grained powders, making the appearance of a powder with less pore space.

Edit: I found a reference for this principle

Soil porosity refers to the space between soil particles, which consists of various amounts of water and air. Porosity depends on both soil texture and structure. For example, a fine soil has smaller but more numerous pores than a coarse soil. A coarse soil has bigger particles than a fine soil, but it has less porosity, or overall pore space. Water can be held tighter in small pores than in large ones, so fine soils can hold more water than coarse soils.

http://www.noble.org/ag/Soils/SoilWaterRelationships/Index.htm