Measuring powder

[jwr0201]

Exactly how is powder measured? I have a friend who swears that he never measures the volume of powder he is using for reloading. He says that he weighs the powder on a scale - in grains only and them loads. Why then, do I read about the importance of knowing the volume of the powder in a particular load one wants? Which brings about another question - is there a conversion formula that is used to convert volume in cc's to grains?

Thanks,

RR

 

[oldracer]

Well when I use the single stage press for .223 and .308 I use a scale only and when I use the Lee multistage press for 38 and 357 it is setup for volume but to play safe about every 15 to 20 rounds I do weigh the powder charge before the bullet is seated just to double check. That multistage can really get to loading so I make myself stop periodically to verify. I have found that a powder such as IMR 3031 sometimes will have the correct weight but seem to really fill the .223 case to the top and I have to sort of tamp it down and then there is enough room for the bullet to seat. I guess that is because it is a rod powder instead of a ball powder?

I would say to try both and see which you are most comfortable with and then go with that.

 

[Dan Cash]

The volume of the charge is critical but darned near impossible to measure and adjust accurately, e.g 3.049cc. Therefore, the weight is generally used to define the charge of powder. If using a measure, it is adjusted to throw a given charge by weight. Should that particular powder take on moisture or lose moisture, a charge thrown by the previously adjusted measure would weigh differently but the performance would probably be about the same. Reloading manuals give charges by weight as that is easily and precicely determined.

 

[Jellybean]

It sounds like you've read Lees Reloading manual.
Powder is measured by weight on a scale, then metered by volume in most powder hanling equipment. Lee sells equipment that measures by volume that uses charts to tell you how much powder (in grains) fits into a certain volume and actual weighing isn't needed. So they say.

 

[1sgpierce]

Powder in Grains

Pretty much all reloading information regarding powder charges is calibrated in grains (7,000 grains to the pound). While some manufacturers sell measures that have a predetermined volume, the basis for that volume is what a specific charge of a specific powder would weigh if checked on a scale. In the case of Lee, he sells plastic dippers that have been calibrated to provide a specific amount of powder that is the same as what the powder would weigh is put on a scale. Your adjustable powder measures (Uniflow, Dillon), do the same thing, adjusting the volume of the measure either increases or decreases the amount (volume) of powder (and it's weight in grains) accordingly. Don't confuse volume and weight, they are apples and oranges.

The other issue is that of case volume and powder positioning. When a load of powder fills the case so that there is light compression of the powder the velocity of that load will be more consistent between rounds. Generally though that can only be obtained in rifle loads. In pistol loads you generally will not fill the case (which can and has led to double charging), but you want to make sure you don't double charge a case (a problem with progressive presses if you aren't paying attention to the reloading process). The key is understanding the basics of the reloading process, and paying attention to detail.

When using progressive presses and adjustable powder measures, you should always check the thrown powder charge using a scale prior to beginning to reload and then every now and then during the reloading process. I had a Dillon 550 for 20 odd years and never had a problem with it. On the other hand I have two sets of Lee powder dippers and will use those when I am throwing together a small number of loads for some caliber I don't use much.

If you reload for handguns, you will find weighing each load a tedious and time consuming process, but some people do exactly that. To each their own. I generally set the powder measure and then check it whenever I pull it off the stand or change the powder charge.

 

[marlin.357]

Powder charge is determined by weight since the volume per weight may vary lot-to-lot, that's why it's recommended you work up a new load with every lot. But it is more convenient to measure by volume That's the way powder measures work. Lee (and maybe others) have worked up charts which give the approximate weight per volume of many (most?) powders. Check the Lee Precision site, here's the page for the dipper set. In my experience the weight will be light for the volume, but that's better (safer) than heavy. Some may complain that it's inexact, but just like seed or nails, it's sold by the pound, not the bushel, count or volume.

 

[Jellybean]

There are a number of other powder meters that are volume based, Lee isn't the only one. But most of them don't bother with giving their bushings a "volume in CC" description because of the very reason marlin .357 mentioned, it changes. And Lee doesn't just make their dippers in CCs, they have a disk type measure that is marked that way as well. But, if you've ever used both of them with the same powder at the same time you will notice that the measurements don't mean squat. The amount of powder you get using the dippers will vary with the way you use them and will probably never be equal to what the disk measure will deliver. But the charges are on the low side and the difference won't cause a problem, unless you are working near max. in your loads.

The other brands of measures that use fixed volumes will have a chart for their bushings or rotors that will give you an idea of what they deliver. They aren't much different than Lees, except in price and quality.

 

[H Richard]

Simply put, you adjust the powder measure by weight to obtain the desired load, which is the volume desired, then drop the powder directly into the case from the measure. Checking every so often to make sure your weight doesn't vary beyond parameters, (+ or - 1/10 grain) in handgun loads and would be a little greater in large rifle cases. Using a ball powder my RCBS powder measure will drop within less than half a 1/10 variance.

 

[wiley]

It may be that some confusion arises in the difference between smokeless and black powder. All stated above is most correct> for smokeless; but the convention for black powder is to measure by volume, even today.

 

[oldRoger]

For Smokeless Powder Only.
To rephrase all of the above;
The common powder measure uses an adjustable cavity which fills each cycle (throw). This is a volume measurement and is only a proxy for the weight.
The formula in the loading manual gives weight not volume. So you adjust the measure to get close to the desired weight as possible with each throw. Having set the measure once we none-the–less continuously check it since conditions in the measure may change (drift).
Many powders do not meter well, that is the cavity does not fill the same each time. Some powder has large granules and they stack differently each time. We expect some variance and normally it is allowable.
Because we are using an inexact proxy we do not trust powder measures when we are near max loads or for extreme accuracy, these we weigh 100%. Sometimes I will set the powder measure to slightly below my desired weight then bring it up to desired weight on the scale.

Roger’s Rule; You can reload safely without a powder measure, but not without an accurate scale.

 

[ExplorerOne]

Interesting discussion, one with no exact answer. The vast majority of loads are weighed, either directly or indirectly. By indirectly I mean the powder measure volume is set by measuring the weight of the powder dispensed. Is a time proven method, and safe when done correctly with decent equipment. And do periodic checks while loading to confirm you are getting what you think you are.

That said, the benchrest world commonly uses volume. The initial setting of some expensive measures is determined, then MINOR adjustments are made on the range to compensate for conditions at the time. THIS METHOD IS NOT FOR AVERAGE USERS! You must you your gun and how it reacts! Few of us reload every 5-10 rounds at the range, nor want to.

 

[fredj338]

Simply put, you adjust the powder measure by weight to obtain the desired load, which is the volume desired, then drop the powder directly into the case from the measure. Checking every so often to make sure your weight doesn't vary beyond parameters, (+ or - 1/10 grain) in handgun loads and would be a little greater in large rifle cases. Using a ball powder my RCBS powder measure will drop within less than half a 1/10 variance.

THis is correct. The volumn of the powder is seconday as it changes with each type of powder. Example, a fully compressed load of say BlueDot in a 9mm exceeds 100% of the volumn, but is safe. A double charge of TG does not fill the case & will spearate the gun from the shooter. All smokeless data is given in grains weight. You use a scale to set the volumn measure of all powder measures & then throw volumn charges. You can also wiegh all charges, both are acceptable & safe methods. Even the LEE dippers are calibrated (although poorly) w/ a scale.