Weight vs. Volume

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Weight vs. Volume

Postby Iplayfarmer » 22 Sep 2017 16

I did an experiment the other day...

I usually weigh my competition loads a little underweight and adjust with a trickler to within 5 hundredths of a grain of my target weight.

A relative of mine swears that volumetric measurement of powders for reloading gives more consistent results. I was short on time to get enough ammo loaded up for my two day competition last week, so I decided to go the pure volumetric route with my low power target loads that I use in Cowboy Action Shooting competition. I used a Lee Autodisk powder measure on top of their powder through expanding die. I still weighed every 20th round or so just to make sure I wasn't loading anything too heavy or too light, but I didn't make any adjustments to the weight.

I shot better than I have in months. I think I'm a believer in volumetric measurement of powder... at least for low power loads in pistol cartridges.

Anyone else had experience contrasting volumetric measurements with weight measurements of powders?
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Re: Weight vs. Volume

Postby GasGuzzler » 22 Sep 2017 17

I'm sure the specific density numbers and type of powder as well as the actual overall load and the gun it's used in are just as influential as the method by which charges are measured and metered.

In short, you likely just found a magic load.
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Re: Weight vs. Volume

Postby mr surveyor » 22 Sep 2017 18

It's Friday and the cheap tequila combined with my dain bramage is gitting to me.... but I've always had a bit of difficulty in differentially considering the relation of weight to volume in powder loads. Lee is big on the volume loads (cc's per load), where most others seem to recognize weights....

Powder weight to volume is always subject to lot number of powder and moisture content ....


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Re: Weight vs. Volume

Postby HarryAlonzo » 22 Sep 2017 19

I've always believed what they say on cereal boxes. "This product is sold by weight, not by volume." And if you bake, you'll know that critical flour measurement is always done by weight. Your Grandmother knew to fluff it with a fork and carefully scoop it into the measuring cup.
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Re: Weight vs. Volume

Postby mr surveyor » 22 Sep 2017 19

that's probably a good analogy!


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Re: Weight vs. Volume

Postby runfiverun » 22 Sep 2017 21

a volume of powder produces a volume of gas.
the volume of gas is what we are concerned about.

we just get there through weight measurements because I can tell you I use 19.3grs of this or that.
it's hard for me to convey .421cu-in and you then having the ability to measure that volume on your powder dump.
so we set our dump to that volume and confirm it on our scale.

a good load works if the measurement is off .2grs one way or the other,, the ladder test proves that out.
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Re: Weight vs. Volume

Postby Ranch Dog » 23 Sep 2017 06

runfiverun wrote:a good load works if the measurement is off .2grs one way or the other,, the ladder test proves that out.

I agree with what runfiverun wrote, and his last statement hit the nail on the head. If your load depends on being spot on the 1/10th of a grain, you are working with the wrong powder.

Everything that I shoot, 25 Auto through 480 Ruger gets dropped by volume. That volume is derived from a weight which is referenced from published load data or QuickLoad.

Many reloaders have a tough time with the relationship between weight and volume because they don't determine the specific gravity of the of their powder and use that for the number crunching that delivers the load at the drop.

I'm a Lee Precision guy and use all their powder delivery tools from the dippers through the new Auto Drum. I'm able to spend all the time I want reloading, but my reloading life is too short to trickle.
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Re: Weight vs. Volume

Postby donhuff » 23 Sep 2017 08

I started loading in 1975, and I learned pretty quickly hat a tiny bit off (.2) in the powder delivery makes no difference in the outcome (velocity/accuracy) of the load. So I quit weighing every single drop, and learned to trust the volume measuring powder measure when using flake or ball powders. Stick powders for big rifles, now that's another story. I do weigh those but only because the danged powder is so aggravating to run through the measure.

But if I'm using ball powder in something like a 223/308 for an AR/m1A, and i'm loading a lot of them, I do juts drop those charges too.

On pistol loads, I'll usually load up 100 empties in trays, and dump powder in all of them after setting the measure. I might check weigh one at round 50, but not always. Because in the past I have never seen the load get off UNLESS the adjustment lock nut, has gotten loose. So instead of checking a drop, I check the nuts tightness every 20 or 30 drops.

I use RCBS uniflow measures, and I have one that the nut gets tighter when I use it to the point that it takes pliers to loosen it. And the other one needs pliers to get the danged thing tight, and then is finger snug when you get finished.
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Re: Weight vs. Volume

Postby mr surveyor » 23 Sep 2017 09

but, when you consider that the weight to volume ratio can vary a considerable amount between different lots of the same powder, there is no strict baseline to use for that volume only powder dispensing system. Do you not have to change/adjust the powder volume dispensing measure system when a different lot of powder is used?

For most "target" loads (for me, midrange loads) of handgun rounds, I'm o.k. with the predetermined volume measure. The possibility of the +/- jump in volume to ratio of the powder is most likely not going to make a dangerous condition.

When I first started reloading I was using nothing but the Lee dippers and the Lee 2nd Ed. and the "slide rule" (powder weight/volume for the dippers) for loading .357 mag. Using the given number of 0.7 cc dipper for dispensing 6.4 grains of Unique, I was happily loading and shooting what was actually a fairly whimpy 5.8 gr by scale measure. I opened another can of Unique and scale measured closer to 6.1 gr with the same 0.7 cc dipper. Those loads were obviously a bit stouter feeling. That was my beginning on developing the habit of staying below the recommended "do not exceed" Max charges. I also found that Mr. Lee was right about the most accurate charges are usually safely below the recommended Max charges anyway.

The texture/condition of the powder has a lot to do with the equation as the "fluffier" powders will tend to get denser if the granules physically get eroded/broken. I would guess that's going to happen to some degree with just normal handling of mixing the powder by rolling the jug and moving the powder back and forth from the jug to the dispenser.

I understand the mathematic concept of weight to volume, but I still believe that the powder's potential is probably better expressed by weight.


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Re: Weight vs. Volume

Postby Iplayfarmer » 24 Sep 2017 12

I still set my powder measure by the initial weight. I changed the disk around until it gave the 4 grains I wanted. Once I had it set, though, I didn't touch it.

I've always ascribed to the "by weight is better" school of thought. Now that I've had the good experience with volumetric measurements my mind is more open though.
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