Powder density variation and loading procedure.

First topic message reminder :

If you open a fresh jug of powder, say Bullseye, and find that it is throwing a slightly heavier charge using a volume powder measure (such as a Star powder bar) than an equivalent previous lot of the same powder, do you keep using that bar and throw a slightly heavier charge, or do you adjust the volume so that the new powder throw weighs the same as the previous lot of powder?

Thanks for any thoughts or experience!

No names please, just call me…

Powder “Curious” in Texas

How you handle the machine matters too. As with any manufacturing process, the First run has variances until things settle in but you as a human add additional variance. Bump the machine, handle slams on up or down stroke, speed of operation, variable bullet hardness, brass lube or lack of it etc etc you can think of more but the pint overall is this is not bench rest pistol, in my opinion , your variables in firing greatly exeed those of loading . Marksmen invariably focus on loading and bench testing in deference to better shooting, l know that l did once. If ya can’t shoot, test!

Bruce, I just saw this.  Advice noted and taken. lol

Merick wrote:I meter powder by mass and not volume, that is how the manuals list it and how dry powders were handled in chemistry class. I figure the total chemical bonds that contain the energy are more closely related to mass, especially for bullseye loads with low to moderate case fill %.

+1 
Totally agree that powder mass is what counts not volume when we are discussing lot-to-lot variation.

hengehold wrote:

Merick wrote:I meter powder by mass and not volume, that is how the manuals list it and how dry powders were handled in chemistry class. I figure the total chemical bonds that contain the energy are more closely related to mass, especially for bullseye loads with low to moderate case fill %.

+1 
Totally agree that powder mass is what counts not volume when we are discussing lot-to-lot variation.

Aren't mass and volume the same? Weight is clearly different. Explain.

Powder is irregularly shaped, so it is not uniformly dense. It will clump up and make little air pockets and do all sorts of naughty things. So, mass is a more uniform measurement than volume.

JRV wrote:Powder is irregularly shaped, so it is not uniformly dense.  It will clump up and make little air pockets and do all sorts of naughty things.  So, mass is a more uniform measurement than volume.  

I think, we are thinking different things, or different descriptions. My thinking:

Given a mixed volume potential, say an empty .45 case,

Fill that case with a dense powder, say BE, then dump and weigh contents on a scale. Say it weighs X. So that volume (mass) of powder weighs X.

Fill the same case with a much less dense powder, say Trailboss, then dump and weigh the contents on a scale. It will weigh much less than the same volume (mass) of BE.

Perhaps mass is not interchangeable with volume. In my mind they are the same. Going to individual granules being shaped differently, is not realistic in reloading since we use many hundreds or thousands of granules in each of our loads. So how they stack in the case or powder hopper may be the determination as to density by volume with multiple granules of powder. FYI, Trailboss for example looks like small Cheerios, so in a given volume, it weighs less than do the solid particles.

I would say that mass and weight are essentially the same, since the acceleration due to gravity is very consistent. Powder morphology and packing mechanics determines the weight (or mass) that fills a particular volume, and not all equal volumes will fill with the same weight of a charge. Humidity can affect charge weights as powder has an affinity for water vapor, which also can affect burn rate in some cases. With pistol charges, I don't think it's a factor, even out to 50 yards. With large rifle charges, it can affect MV and long range results.

Just to be an engineering pedant, what we load is actually mass, which we determine by weight.  Weight is mass multiplied by the acceleration of gravity.  With gravity being relatively constant we can get away with determining mass by weight.  

What JRV is referring to is the “bulk density” which is the amount of mass of the powder in a given volume.  That does vary between powders and even between lots of the same powder.

Wobbley wrote:Just to be an engineering pedant, what we load is actually mass, which we determine by weight.  Weight is mass multiplied by the acceleration of gravity.  With gravity being relatively constant we can get away with determining mass by weight.  

What JRV is referring to is the “bulk density” which is the amount of mass of the powder in a given volume.  That does vary between powders and even between lots of the same powder.

To further the pedantry, a balance measures mass, and a scale measures weight.

Merick wrote:

Wobbley wrote:Just to be an engineering pedant, what we load is actually mass, which we determine by weight.  Weight is mass multiplied by the acceleration of gravity.  With gravity being relatively constant we can get away with determining mass by weight.  

What JRV is referring to is the “bulk density” which is the amount of mass of the powder in a given volume.  That does vary between powders and even between lots of the same powder.

To further the pedantry, a balance measures mass, and a scale measures weight.

So, someone has to ask!

What would the difference be between 3.8 Bullseye measured on a balance and 3.8 Bullseye measured on a scale?

It's discussions like these that send new shooters off the deep end searching for "accuracy". 

DA/SA wrote:
What would the difference be between 3.8 Bullseye measured on a balance and 3.8 Bullseye measured on a scale?

It's discussions like these that send new shooters off the deep end searching for "accuracy". 

No difference.  Gravity is a constant.  

A balance functions by comparing two objects, one of which has a known mass (usually a calibrated measure or set of measures).  A scale measures the downward force (more accurately, the direction of force moving towards Earth) imparted by an object. 

If you went to the moon, or somewhere with reasonably different gravity, your scale would be useless without enough data to model the new gravity.  However, a balance would still function. Two objects with a mass of 100 grams would still balance out, even if they were “lighter” due to lower gravity.

So, whether you use a good balance or a good scale, so long as you’re on Earth and at a normal elevation, you’re going to get the same results.  3.8 grains.

That was my point.

Thank you!

DA/SA wrote:

Merick wrote:

Wobbley wrote:Just to be an engineering pedant, what we load is actually mass, which we determine by weight.  Weight is mass multiplied by the acceleration of gravity.  With gravity being relatively constant we can get away with determining mass by weight.  

What JRV is referring to is the “bulk density” which is the amount of mass of the powder in a given volume.  That does vary between powders and even between lots of the same powder.

To further the pedantry, a balance measures mass, and a scale measures weight.

So, someone has to ask!

What would the difference be between 3.8 Bullseye measured on a balance and 3.8 Bullseye measured on a scale?

It's discussions like these that send new shooters off the deep end searching for "accuracy". 

Hey now, that hurts! lol

My original question was partly out of curiosity and partly thinking about how to handle density variation. 

The variation I got was higher than I thought to expect.  Hygroscopic powder was one possibility, thought I store it in its sealed jug inside the house. Lot to lot another likely candidat… fine particle settling…

Back to dry firing…

Let me chime in with "monkey wrench".  IMHO..........  Unless one or another reloader use highly precised, calibrated and regularly certified scale or weights 3.8gr BE (or any other powder, or any other measurement) represents nothing else but a number derived through using particular set of tools.  DA/SA's question is not that simple if we need to achieve absolutely accurate number, especially if we are to measure beyond one decimal.  3.8gr measured by one reloader on own equipment for sure will show different number if EXACTLY SAME DROP moved over and measured by second reloader on another equipment.  The good news is that we do not need such a precision when it comes to dropping charges.  Numbers that we exchange are only representative of one's (presumably) testing or particular charge against print on the target.  Results most definitely will be different if tested by another tester.  (Testing, Testing, Testing! - and that is the answer to OP's question!)  Hence issue boils down to dropping consistent charges, or let me re-phrase it, - seeing the same number (with allowed variance) for multiple instances when measured using the same tool(s) in same environmental conditions during limited period of time.  Drop -> Number, Drop -> Number, repeat....., and TRUST your equipment.  It is that simple.  No need to overthink it.  My good friend keeps telling me that "... shooting 10 is simple!".          

AP

One thing to also consider is the question “How much powder charge variance matters.?”.  In my testing that answer is that the powder charge variance from ordinary loading processes does not result in inferior ammunition. (I know most of you have seen this photo before, but it illustrates the point.). These are targets to use up test ammo for my wadgun (not the pistol shown). These are shot with my S&W 745 which I use as a training pistol.  The ammo was loaded with two powders, Bullseye and 452AA, and the same charge weight span 3.8, 4.0, and 4.2.  All charges were fired at the same target.  While there are flyers, most of them were called.  

The upshot is, that ordinary powder variances don’t make enough differences to warrant special treatment when loading pistol ammunition.  There’s more differences in powder selection.

Greetings,

I tested five (5) different lots of Bullseye ranging from 1994 to 2013 production date.

Same powder bushing, all I did was swap the powders and weigh them.

The "weight" did vary; but, the "volume" was the same.

Personally, I do not think it is worth concern.

45 Colt Gold Cup barrel mounted in a mechanical fixture. 

Distance it 50 yards.

First target is the backer and contains all five groups plus sighters/foulers.

Cheers,

Dave

Dave, thank you!  Very enlightening and I value your opinions.  As I do appreciate everyone’s thoughts and input. 

Rod