Weight vs Volume...Huh?

[Big Caliber]

I've always loaded my rifle cartridges by weight. I read a post on this forum that the benchrest shooters load by volume. Logic tells me they probably have cases that are identical in shape and capacity. But how do you actually determine consistant loads from case to case? I guess my question is, What is the volume method? Thanks in advance.

[LHB1]

Load by weight = use a scale to measure each powder charge.
Load by volume = use a powder measure to throw powder charges. A scale is used to test thrown charges to determine correct setting of powder measure beforehand.

[Big Caliber]

Well, is the correct setting of the powder measure determined by weight? If so, that's how I've been doing my handgun loads. I don't mean to be stupid, I'm just practicing for my old age.:D Is this method more "accurate" than weighing each charge?

[LHB1]

Yes, as stated in the prior post, the powder measure is set by weight. Using a powder measure is not more accurate than weighing each charge but it is MUCH faster and sufficiently accurate for even the benchrest group when done properly.

[rc]

Weight and volume are related by density. We use volume to measure a specific weight. It's the density of the loading that helps insure consistent handloads. We want air space at a minimum so we tend to pick powders that at max charges will fill between 90 and 100 of avaiable space. Some powders build pressure so slowly that even a case full of powder is "safe" and that's where you see the letter "C" after a charge weight in reloading books indicating the bullet compresses the powder charge which has filled the case. I believe most accurate loads are generally below max but fill most of the space in a case.

[WESHOOT2]

Weight may vary based on environmental conditions (moisture content of the powder can vary), but volume will not for most powders.

[Big Caliber]

So then...powder density must not be much of an issue when using modern smokeless propellants, correct?

[30Cal]

You might also consider that the typical amount of charge variation you see from a powder measure doesn't really matter on a target.

[Big Caliber]

Thanks for all the input. I guess I'm too dense between the ears, I just don't get it. It seems like your committing a lot factors to "faith" where, like doubting Thomas, I gotta see exact, identical measured charges.

[30Cal]

I do my load development with worst case parameters. I shoot 10rd groups with my worst brass. Half the rounds in that group are intentially left 0.3grs light on powder, the other half are 0.3grs heavy.

This relieves me of the burden of having to worry because I know that whatever I load for real will always be better than what I tested with. It's very baffling to me why the bulk of handloaders are focussed on testing solely for the absolute best-case. It's like building a car from cherry picked components and then only testing it at a constant 50mph on a dyno in an air conditioned room.

Aside from what's necessary for safety and reliable function, the bullet holes are what I focus on.

[Mike Irwin]

"It seems like your committing a lot factors to "faith" where, like doubting Thomas, I gotta see exact, identical measured charges."

Well, with a given powder of a given lot, a certain weight will take up a certain volume. That's the entire concept behind volumetric powder measures.

You can have weight variances in the thrown charge, that is true, but it's been proven many, many times over the years that when it comes to accuracy and safety volumetrically measuring a charge is, in many cases, just as effective as weighing each charge and, when the round is tune to the rifle, will provide exceptional accuracy.

Hatcher recounts an incident at the National Matches years ago. The ammo provided for the National Match course (would have been .30-06 sometime in the 1920s or 1930s using IMR powders) had been volumetrically loaded.

One competitor decided to weigh a bunch of charges and discovered what he considered to be a large charge weight variance, IIRC 3+ grains. He complained loud and long about how terrible this was, but he ignored the fact that there were more National Match records set with that batch of ammo than in previous years, so obviously the arsenal technique was sound.

What's often more important to fine accuracy than exact weight of charge, at least in rifles, is loading density in the case. Stick powders like the IMR powders can give a greater loading density variation (and weight variation when thrown from a volumetric measure) simply because of their shape, whereas ball powers like Winchester 748 will tend to pack in the case and the measure a lot more consistently due to its shape.

That said, reloaders using both types of powders prove that extremely fine accuracy with perfect safety is possible using volumetric measurements.

[azredhawk44]

Take a look at page 704 in "Modern Reloading: Second Edition" By Richard Lee.

It gives the VMD (Volumetric Density) of many popular powders, both black and smokeless.

For example, the VMD of IMR-4895 is 0.07280.

That means 1 grain of 4895 has a volume of 0.07280 cubic centimeters.

If I knew that my powder charge I wanted was 42.0 grains (consulting my load data), I could set my volumetric powder measure to 0.07280 * 42.0 and get a result of 3.0576 cubic centimeters.

An RCBS Uniflow and most other volumetric measures will have cubic centimeter measurements on the adjustment bar. If you set it at 3.05 and throw a couple of settling charges then measure a good throw, you'll be right in the ballpark of 42 grains.

[Big Caliber]

Hmmm...I'm beginning to see the light. I use that method for loading my pistols. I suppose there is no real reason to not do the same for rifle loads. I'll have to try it. Thanks guys for the answers and your patience. BC

[jeremiahjj]

We can relate this matter to drinking booze. Most spirits (hard liquor) are 1.5 ounces of 80 proof, or 40 percent, ethanol. Once in the body the alcohol, being infinitely soluble, is absorbed into the blood stream and distributed throughout the body (68 percent water for a man, less for a woman) in what's known as a blood alcohol concentration. But when we attract the attention of the police, it is breath alcohol that usually gets measured. That's because the partition ratio (roughly 1:2100) can tell us how much alcohol is in the blood. But when we end up in court, the experts calculate back to when we were kicking back a few at the bar. But rather than go through all this, it's easier to say we had (for instance) six 1.5 ounce scotches. This is what is known as a volumetric measurement. So just come up with a similar way of measuring your powder and you're there. Just don't use ounces because, in addition to being inappropriate, that would take you back to weight again.

There now, wasn't that easy? :D

[F. Guffey]

Big Caliber, If you have stick powder and purchase a Uniflow powder measure you can expect two things to happen, one, the sticks are going to get cut, for me that is not a problem, two, careful attention must be paid to the funnel system, stick powder can bridge in the funnel.

If you have a Uniflow powder measure and purchase powder there are options, SS (short stick) powder is available along with powders that are not likely to be cut with the rotor drum.

Measuring with a dipper and measuring with a powder measure? The Greeks call that 'iso, iso' meaning 'same'o, same'o', I have old shotgun measures that are adjustable for shot and powder that go all the way back to 'handles'. cut down pistol cases with wire handles that are soldered, if you were weighing charges before there is no reason to change, use a dipper or Uniflow powder measure first then trickle to finish.

I have Lee dippers, yellow and red, Dillon 550B syetem, RCBS Uniflow and Little Dandy, Lyman, Ohaus etc., when weighing charges I use the Uniflow then trickle, I find the Little Dandy most accurate, after loading 250 30/06 cases with the Dillon 550B I found a 16 grain spread all traceable to the difference in case weight between Winchester and R-P, Fedral and military, There is all kind of advise for cures when using stick powder in a progressive press, polish, shine, smooth the inside, etc., I do not use stick powder in a progressive, if the powder can bridge, it will.

If I use a progressive press I know the weight of the primer, case, bullet and powder, even though the press measure by volumn I adjsut it to weight and eliminate the twlight zone by weighing the finished product and compare with the total weight of the components.

F. Guffey