Powder density variation and loading procedure.

by RodJ Fri Nov 24, 2023 1:11 pm

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

by bruce martindale Fri Nov 24, 2023 1:47 pm

I don’t change anything, but I keep same batch ammo together especially for SF. As with anything “If you think you need to, you do”

by RodJ Fri Nov 24, 2023 4:18 pm

Thanks Bruce. That makes sense.

by Merick Sun Nov 26, 2023 9:23 am

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 %.

by John Dervis Sun Nov 26, 2023 8:11 pm

You bring up an interesting question. It’s been quite a while since I have opened a new jug of powder so I can’t say I specifically check a new container when I open it. I do check my powder drop from time to time just to make sure nothing has shifted. I do that test by throwing 10 charges and averaging the result. My powder measure doesn’t really ever change but it gives me piece of mind if I haven’t loaded for a while.
To your question specifically, I would adjust my measure so it throws the same charge that it did before unless there was a documented manufacturing change with new loading data that says plus .2 grains (or whatever the overage is) is the new normal. I don’t think Bullseye powder has changed much over the last century but I suppose some other brands might change so you would have the situation you describe.

John

by RodJ Sun Nov 26, 2023 9:57 pm

Thanks Merick and John. Wondering whether the “cause” of the density change affects whether to change the charge weight. Humidity? Particle size? More or less inert material?

As I think about it, it argues for retesting loads when changing lot numbers. Of course I’m loading soft loads, so I’m not terribly concerned about overpressure. But consistent velocity and general accuracy would be relevant (If I were a better shot, that is.)

Thanks again for all the replies!

by chiz1180 Mon Nov 27, 2023 6:29 am

I don't change anything on my powder measure unless their is an apparent need (ammo function, recoil impulse not right, ect.) One thing that I do that mitigates any immediate change lot to lot, is I work from two containers of powder a "new" container and and "old' container. When I start my loading session I fill the measure from the "old" container and top off the level from the "new", when I finish loading I empty the powder measure back into the "old" container. Different lots of powder can have some differences in performance, If I had a chronograph I would probably do lot testing of my ammo, not that I would expect massive changes but just out of curiosity.

by BEA Mon Nov 27, 2023 8:46 am

New powder lots are always tested by the same methods. There is a primary test and a secondary test. For instance, Bullseye might be tested in a 38 special as a primary test, and perhaps 9 mm as a secondary test. They have to meet standards for density, velocity and pressure. There is a standard lot maintained in the ballistic lab and new production lots are fired against the standard. The test results have to fall within a given window for all 3 criteria. If it does not, the lot fails. In addition, "reference ammo" is used to verify the test barrels. This ammo is specially manufactured to operate at a given velocity and pressure. When reference ammo is fired through the test barrels, the variation in fps and psi from the levels that that ammo is prescribed to operate at are recorded. This deviation is taken into account when testing the ammo loaded with the new lot of powder. This is known as the "correction" and it accounts for wear in the test barrel over time. Manufacturing powder is a complicated process as is quality control and it is impossible to make each lot of powder exactly the same. A great deal of effort goes into delivering a consistent product to the reloaders. The time and trouble that a reloader goes to to account for the lot to lot variation is a personal decision. It has to be weighed against the potential benefit in ammo consistency vs spending more time practicing with the result hopefully being higher scores. Good shooting.

by RodJ Mon Nov 27, 2023 1:29 pm

Fascinating. Does the manufacturer use the same weight charge or volume charge? I’m assuming weight and that solves my curiosity.

by mbmshooter Mon Nov 27, 2023 1:43 pm

RodJ wrote: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

Rod,

I can't comment on the reason for any weight variations on newly-opened jugs of Bullseye. I didn't notice any difference when I opened a new 8# jug a couple of months ago.
I was fortunate to acquire a couple of adjustable powder bars for my Star so I simply make whatever "tweak" might be necessary to attain my desired weight drop. I use an electronic scale before each session and, of course, when I'm changing from LSWCHP to JHP. I haven't used the Star fixed-size powder bars in many years.

Mike

by BEA Mon Nov 27, 2023 2:02 pm

In the quality control testing procedure, the same powder charge, same brand/weight bullet, primer and the same brand of brass are always used. When they get in a new lot of brass, it is tested. They use a procedure where they test the amount of force it takes to "offset" or expand the brass. This force is calculated into the pressure produced during firing. Different lots of brass can have different offsets.

As far as changing bushings, if a new lot of powder is dropping a slightly different weight...you can do this if you want to, if your bushing is adjustable. Personally, I used a Star loader with a factory charge bar and just kept on loading. When reloading press companies set up their charge bushings/charge bars, some may simply use whatever lot of powder they have on hand to set the bushings. This will certainly work and it is safe, but depending on the lot of powder they use, the density could be anywhere within the allowed window. With the next lot of powder, it could have a density on the other side of the window, which might show up in your test weighing. Ideally, they would obtain some of the "standard" powder for the type they are testing so that their bushing would hopefully drop pretty much in the center of the ballistics window, but this is not always possible. With powders that are imported, it is very likely not possible.

by RodJ Mon Nov 27, 2023 4:13 pm

Dang a lot of knowledge! The BE powder was just an example. I have a Star and use bushings made by Bruce at Star Machine works. He machines them to dimensions that match published VMDs but he cautions, appropriately, to confirm the actual weight with your lot of powder. Got me thinking.

by john bickar Tue Nov 28, 2023 8:32 am

It should be noted that BEA, in addition to being a High Master in Bullseye and a two-time Olympian, also has extensive professional experience in propellant manufacturing. His bona fides check out.

by **PhotoEscape** Tue Nov 28, 2023 9:07 am

I want to add one more piece to the puzzle here. What one reloads caliber wise must be taken to account. While variations of the density from lot to lot might not have much of the affect while loading 45 ACP, and same bushing (on Star) or same setting of the powder bar (on Dillon) can be used, it is not so when loading 32 WC or even 38 WC. I recommend batch testing for such calibers every time powder lots are changed.

In my reloading experience I had one very significant variation with BE powder. Very old lot of BE manufactured by Hercules was noticeably less potent than currently manufactured lots of BE, and required increase of charge by 0.34gr in 38WC load. I do not believe it was due to environmental conditions as 1# paper container with old lot was sealed and in great conditions overall.

AP

by Allgoodhits Tue Nov 28, 2023 9:21 am

Great info, especially from BEA. Thank you.

I do not leave powder in my powder dropper, thus it goes back into the original powder container. I put cap on tight. When ever I am about to pour powder into the hopper, I gently rotate the jug a couple times to mix the powder. Over time I notice small amounts of powder dust in the jug. More dust as the jug or container empties. I think by rotating the jug/container this distributes the smaller particles in with the normal particles or granules. Maybe it doesn't help or do anything, but it is what I do. It makes me feel better, and some powders it may make more sense than others.

Weight vs volume? I believe that loading is done by volume of a given powder. We use a scale as a convenient means of measuring that volume by weight. It then becomes fairly easy to repeat that amount of volume, since we know what it weighs. When I reload, I notice that the weight varies a very small amount. I don't worry about that as long as the "setting" on the powder dropper has not changed. If it hasn't changed, then the volume is the same. So which varies more, volume or weight? I don't know, but I like the volume approach, then check the weight it make sure something not out of wack.

by **PhotoEscape** Tue Nov 28, 2023 9:46 am

Allgoodhits wrote:Weight vs volume?

This is very interesting and fundamental question. IMO weight approach is prevalent as this is something reloader can actually measure. Volumentric approach is less controllable as volume of the cavity (bushing or bar setting) doesn't translate into the same volume of the powder every drop. Many factors affect volume of the powder going into the cavity from one charge to the next one. "Silo effect" is applicable to powders to begin with, and then level of the powder in hopper, and many others including consistency of reloading operation. Without introducing external agitation (i.e. vibration, pressure, etc.) consistency of powder volume filled into the cavity of powder bar varies.

I also want to mention that based on my experience Star presses provide for more consistency with volumetric approach. I believe, it comes from the press design, - powder drop is not case activated. Hence there is lesser affect from variations in case length and reloader itself.

AP

by Merick Tue Nov 28, 2023 10:51 am

I have weighted enough charges out of a uniflow to see and extreme spread of half a grain or more.

Now that was a whole lot of charges, and the odds of seeing a real two+ sigma tail risk round in a match are low, but not zero.

Meanwhile weighed charges are nearly as good as my scale resolution.

*It never occurred to me to dump weighed charges into a graduated cylinder to see what they were doing volume wise. That would be an interesting experiment if anyone has the equipment to try it.

by BEA Tue Nov 28, 2023 5:34 pm

Allgoodhits...about the dust in your powder container...I always shake a powder container before pouring the powder out. There are always going to be some "powder fines" or "tails" present, but there is a screening process that removes most of them. Some of the dust may be graphite. A specified amount of graphite is added to improve flow and reduce static buildup.

PhotoEscape...you are correct. Metering small powder charges can be tricky and small variations in charge wt matter more. It is very possible that you had a lot on the slow side of the allowed deviation. If your powder was in a paper container, it has been around for several decades, but if stored in a cool, dry location, it should have still been fine. Regardless of how powder is stored, sealed or not, it does have a shelf life. The warmer the storage temp, the shorter the shelf life.

Hi John! Thanks for your vote of confidence. Coming from you, that means a lot. I hope you and your family have been doing great.

by inthebeech Wed Nov 29, 2023 5:31 am

If I had to bet whether it was myself and my technique, or an actual change in the bulk density of the powder, I'd say that I was doing something differently. I can't say how many times I've loaded the hopper, gone through my start up procedure (check my powder bar setting, tap this, fill up to here, tap some more, calibrate my scale, throw my sacrificial charges to settle everything in...) and when I threw my first official charge for record, came up .1 or .2 grains off from where my chart says I should be. I used to redo my chart. Not anymore. I am pretty confident that I'm doing something different or it is just that my measure wants more than the standard ten sacrificial shots before settling in. Now, if you are going back and forth between two kegs, multiple times and you are repeatedly getting the same discrepancy, then I'd seek the advice of the manufacturer.

by Allgoodhits Wed Nov 29, 2023 7:52 am

BEA wrote:Allgoodhits...about the dust in your powder container...I always shake a powder container before pouring the powder out. There are always going to be some "powder fines" or "tails" present, but there is a screening process that removes most of them. Some of the dust may be graphite. A specified amount of graphite is added to improve flow and reduce static buildup.

PhotoEscape...you are correct. Metering small powder charges can be tricky and small variations in charge wt matter more. It is very possible that you had a lot on the slow side of the allowed deviation. If your powder was in a paper container, it has been around for several decades, but if stored in a cool, dry location, it should have still been fine. Regardless of how powder is stored, sealed or not, it does have a shelf life. The warmer the storage temp, the shorter the shelf life.

Hi John! Thanks for your vote of confidence. Coming from you, that means a lot. I hope you and your family have been doing great.

Thank you Ben.

by Allgoodhits Wed Nov 29, 2023 8:00 am

inthebeech wrote:If I had to bet whether it was myself and my technique, or an actual change in the bulk density of the powder, I'd say that I was doing something differently. I can't say how many times I've loaded the hopper, gone through my start up procedure (check my powder bar setting, tap this, fill up to here, tap some more, calibrate my scale, throw my sacrificial charges to settle everything in...) and when I threw my first official charge for record, came up .1 or .2 grains off from where my chart says I should be. I used to redo my chart. Not anymore. I am pretty confident that I'm doing something different or it is just that my measure wants more than the standard ten sacrificial shots before settling in. Now, if you are going back and forth between two kegs, multiple times and you are repeatedly getting the same discrepancy, then I'd seek the advice of the manufacturer.

FWIW, I find some powders are consistent from the first throw to the hundredth throw. I find that with WST, I have to throw about ten throws before it settles down. With WST it tends to throw more, progressively until it settles down after about ten throws. I also find that WST appears to have more static cling than any other powders I have used. I do like WST, regardless. I have my wife save the BOUNCE sheets from the dryer. I use them to wipe down the inside of the powder measure. It seems to help reduce static, especially with WST. Off topic, I also put a BOUNCE in when I am vibratory cleaning my brass. It absorbs some of the dirty dust from the corn media, and makes it smell good! It seems to make the brass more shiny too.

by john bickar Wed Nov 29, 2023 9:28 am

Allgoodhits wrote:I have my wife save the BOUNCE sheets from the dryer.

You know, it is possible for you to do the laundry too Laughing

by Allgoodhits Wed Nov 29, 2023 11:01 am

john bickar wrote:
Allgoodhits wrote:I have my wife save the BOUNCE sheets from the dryer.

You know, it is possible for you to do the laundry too

by RodJ Wed Nov 29, 2023 1:38 pm

Allgoodhits,
That is interesting to read your observation on WST throws getting heavier until it stabilizes. That seems to be true for my Star setup with WST. I’m going to do some testing. I realize vibration will pack the powder until it stabilizes m but WST seems especially prone to tossing several tenths more for a while. Maybe, too, the fines are working their way down through the powder column.

BEA and others, this is some seriously interesting and helpful info. I’m going to start rotating my jugs of powder to distribute fines each time.

by Eindecker Fri Dec 15, 2023 11:41 pm

RodJ wrote:Thanks Merick and John. Wondering whether the “cause” of the density change affects whether to change the charge weight. Humidity? Particle size? More or less inert material?

As I think about it, it argues for retesting loads when changing lot numbers. Of course I’m loading soft loads, so I’m not terribly concerned about overpressure. But consistent velocity and general accuracy would be relevant (If I were a better shot, that is.)

Thanks again for all the replies!

its changes in atmospheric conditions.. remember on a different board, a guy loaded up x amount of cartridges from a single can of powder, in arizona. Relocated to kentucky, pulled the bullets from each cartridge. let them sit an hour and re weighed each one. they were all changed in weight using same scale.

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