volume/weight/volume

[George]

A continuing point of confusion is the concept of measuring black powder by weight and/or by volume. It’s not surprising that new shooters have a poor understanding of it, I guess, but it seems that some experienced old hands have the same problem. Maybe a brief back-to-basics demo would be helpful.

This is 70 grains of Goex 2F powder:



Here is that very same powder in the pan of a digital scale, showing that it weigh 70 grains”¦. being measured by WEIGHT:



Here is that very same powder which has been poured from the pan of the scale into an antler tip measure carved to hold exactly 70 grains...being measured by VOLUME:



Once more... the same powder poured back into the pan of the scale, and still weighing 70 grains.



It’s important to understand that it’s all the same powder.

Pour it into the antler, it’s 70 grains by volume.

Pour it into the scale pan, it’s 70 grains by weight.

However you measure it, 70 grains is 70 grains.

All the same powder, nothing added, nothing subtracted.

The take away is that any specific amount of black powder has both weight and volume, at the same time, and both stay the same, all the time.

There is no difference between 70 grains measured by weight and 70 grains measured by volume.

Spence

 

[coloradoclyde]

True....if your volume measures are calibrated to the scale..

Spence, how did you measure the pile in the first picture?

 

[coloradoclyde]

Just for giggles...I just took a Lee powder dipper, the biggest one I had. A 4.3cc dipper is suppose to weigh 63.2 grains using 2f black powder.( according to their chart)
I measured and weighed and it weighed 63.3 grains
Close enough for me.... :thumbsup:

 

[coloradoclyde]

Now where it gets dicey is my sliding funnel top measure set at 70 grains measures 64 grains by weight with 2f and if I switch the Lee dipper to 3f the chart says 68.5 instead of 63.2

So you can see things have to be properly calibrated.
2f,3f 4f, pyrodex etc... all weigh differently by volume respectively.

 

[Stumpkiller]

Spence - now take your 70 gr measure and fill it level with FFFg. When you weigh it you'll have about 74 gr. Try it!

 

[M. De Land]

That happens to be true in this one case but is most definitely not true in every case with differing lots of the same powder and granulation or other brands of powder.
Much depends on grain uniformity and moisture content between not only differing brands of powder but also lots of the same powder.
Goex for one tends to have more fines in it than does Swiss for instance both of which I use a lot of.
When you get near the bottom of a can and the fines start mixing in with the whole grains the volume will change as it is more dense.
This is made very plain when one has to drop tube powder charges into cases to get a consistent powder column height for an even compression of powder under the seated bullet.
Match muzzle loaders for long range work also will drop tube their charges for even and consistent powder compaction.
This if very important to maintain elevation consistency in particular.

 

[coloradoclyde]

I just rechecked my swing top adjustable measure using 3f and a 70 grain setting ....it weighed 65.5 :shocked2:

I didn't know that.... thanks spence...You helped me discover that my volume measure was off... :thumbsup:

 

[Stumpkiller]

I have some adjustable measures that are marked in grains (supposedly). One that only says "Italy" for a brand/origin throws 124 gr of FFg at the "100" setting. That's enough to be slightly concerned about.

My T/C adjustables were very close.

 

[coloradoclyde]

I'll say :shocked2:

Thanks Spence, :haha: now I'm running around checking all my measures....

 

[George]

Spence - now take your 70 gr measure and fill it level with FFFg. When you weigh it you'll have about 74 gr. Try it!

I have tried it, many times, and know you are correct. That's completely beside the point.

It should be obvious that volume-weight equivalence doesn't hold true for everything in the world. Ever hear of apples and oranges? Fill that antler tip with #6 birdshot, it will be 70 grains by volume, but weigh it and it will weigh 398 grains. Use #7 1/2 shot and it will still be 70 grains by volume, but will weigh 427 grains.

You calibrate your scale, I assume. Well. you have to calibrate your volume measure, too. If you want to weigh two granulations of powder to highest accuracy by volume you either have to make two antler measures or keep track of how much of each granulation the one measure throws.

None of this has any bearing on the fact that volume and weight measurements of black powder are the same, but you have to do it correctly, it ain't magic. :grin:

Spence

 

[necchi]

You have a hand made measure,
Either you or another person made it,, who ever made it,, made it to hold 70grns of powder by weight.
It is a specific hand made measure.

I'd wager a significant amount,, that any of my store bought adjustable brass measures would need a different setting to hold that same volume then the "7" line on the marked rod.

Just sayin,, your measure is special, it's volume is made for that specific weight.

 

[coloradoclyde]

yep! volume is calibrated to the volume grain weight of BP....

Now I understand what you initially were trying to say...:thumbsup:

 

[George]

That happens to be true in this one case but is most definitely not true in every case with differing lots of the same powder and granulation or other brands of powder.

What I'm talking about here is the theory, not our ability to measure accurately. It's dead simple grade-school stuff. If you make a volume measure to hold exactly a certain amount of black powder and weigh it, it will weigh that certain amount. Exactly. If you can't fill the measure exactly the same each time, if you switch granulations, if you switch brands, if your scale isn't properly calibrated, yadada, yadada, yadada,... then all bets are off. What I'm talking about here is the physics behind what we try hard to do every time we load our gun. I can't do it perfectly, don't know anyone who can. I never measured exactly the same volume of BP twice in a row in my life, but that has no effect on the idea behind what I'm trying to do.

Spence

 

[George]

You have a hand made measure,
Either you or another person made it,, who ever made it,, made it to hold 70grns of powder by weight.
It is a specific hand made measure.

I'd wager a significant amount,, that any of my store bought adjustable brass measures would need a different setting to hold that same volume then the "7" line on the marked rod.

Just sayin,, your measure is special, it's volume is made for that specific weight.

Well, for God's sake, necchi, we aren't talking about the quality of our measures. If I'm using manure gear I'll get manure results, of course, but that doesn't have anything to do with what the real deal is.

Do you use a bathroom scale? Believe what it tells you? You surely understand your actual weight is a real value, a fact, and doesn't change according to what your scale says it is. In discussing the relationship between volume and weight I'm talking about the real deal, the actual equivalence, not what my clumsy efforts using junk gear might say.


Spence

 

[necchi]

Well then we can disagree.
Volume and weight of the same amount of powder are seldom equal.
Yours is in this case because they where specifically matched.
The real deal in this case is, Your custom measure is made to hold 70 weighed grain of Goex 2F powder.
It's no more complicated then that.

 

[coloradoclyde]

I think he means that....when measuring using a volume measure it's difficult to be consistent.....

Or maybe he means something entirely different... :idunno:

 

[George]

Think about what you just said. My measure was made to hold exactly 70 grains so of course when I fill it and measure the weight, it's 70 grains.

You said the volume and weight were exactly equal.

You did't want to say it, you didn't mean to say it, you didn't know you said it... but you said it.

That what I'm saying, too. :haha:

Spence

 

[Stumpkiller]

I believe the bathroom scale - though my doctor's is different. ;-) That or I wear six pound shoes.

But if you ask me my volume I'd be at a loss. Either cubic inches or centimeters . . . not a clue. We use what we have. And a grain scale is a good investment.

 

[coloradoclyde]

Spence.....you're making my head hurt.... :haha:

 

[jethro224]

Good demonstration Spence. :thumbsup:

One thing that maybe should be mentioned for those who use the substitute powders; that same measure filled with substitute powder will weigh considerably less than the same measure of blackpowder. One should NEVER use a scale to weigh out a 70 grain (or whatever) charge of substitute powder. The subs are designed to be volume equivalent to the real thing, not weight equivalent.