Powder: shapes, sizes, weights and volumes

Vern

Vern

Morethan1waytoskinacat
I understand the basic difference in the production of ball powders and the stick powders.

My questions or thoughts come from our measuring of the stick powders.
I think everyone for the most part would agree that when it comes to throwing, ball powders are much better.
Stick powders though seem to come in a variety of thicknesses and lengths.
1. Why is this? What is the criteria for the exact shape length and thickness for stick powders?

2. Depending on the answer to number 1 above. Is it possible to, for ourselves, alter the size of the kernels?

I know that safety in the process would certainly be one issue.
I would think that the burn rate could change but that could be accounted for.
What are the possibilities and problems?
 
Powder burning rate is controlled by grain shape and size as well as coatings. Changing the size of a powder's grains will alter its speed. I think that for all practical purposes, the short answer to your question is No.
 
Boyd to be honest I pretty much knew it was a no. I figured it would have to do with burn rate.
But you never know till you ask. Sometimes simple questions start whole new ideas.
Thanks
 
On another thread you know of.
A comment was made that we measure by weight but powder burns by volume.
I always thought it was the other way around.
I sent a pm to Henry to see what he says.
Mike posted something similar to what I always thought that it burns by weight.
Which is why I tried to go to weight years ago. But that aside I thought if we could some how grind it down so that it would meter as uniformly as a ball powder then.......
Well I think you see where I was going with it.
I know trying to convince the mfg.s to create it that way would only be a waste of time besides there so many powders out there it would be unlikely.
So I thought if there were some way we could do it ourselves and have it be consistent and accurate we could eliminate at least part of the measure and throwing issues.
 
I have a friend who argues that burning rate (or performance) is modified by the amount of residual solvent remaining in the powder. He claims that this occurs progressively as a large jug is used up, so when he buys a new one, he immediately breaks it down into 1 pound jars to use. If he is correct, then the rate of change because of solvent leaching would obviously be related to the rate of leaching. Keep it longer & use it in little bits, then the leaching would be greater; use it quickly in big doses & it would be a less critical issue.

However, if it is a valid claim, then neither measuring by volume or my weight would necessarily be the right answer, unless the leaching were minimised in a manner similar to what he suggests.

I suspect that he is correct, based on one anecdotal instance. I used to toss the tailings of a batch of a particular powder I used regularly in quantity into a "winings jar" & used it when I knocked up loads to run in barrels & the like - nothing competitive. Eventually, when the jar was fullish, I was caught out before a belly match without powder, and used the tailings. The load shot quite well, but with flatter trajectory across the distances than usual, indicative of a higher velocity load, though I never shot it across the screens to confirm.

However, shooting a particular load with the 2006 batch Viht N550 over a 3 year period (supply is problematic here in Australia), always weighing loads on a milligram scale , I recorded velocity variations of less than 20 fps season to season. Is there any significance there?
 
It's always been my understanding that smokeless powders were meant to be measured by weight rather than by volume, while with black powder it was volume that counted. Measuring stick powders by volume can be done fairly accurately on a volume per weight basis if the granules are small and uniform. Unfortunately some stick powders granules vary a great deal in length.

I'd be willing to bet that it would take some good pressure and velocity measuring equipment to confirm or disprove John's friend's idea, it's just too bad it's not available.
 
What is the criteria for the exact shape length and thickness for stick powders?
Click to expand...

Big question……… A few excerpts from my notes.

The energy of smokeless powder is determined by the formulation of the powder; the morphology (particle geometry or shape and size of granules) of smokeless powder adds specific burn rates qualities. Surface area of a powder grain is determined by its geometry and surface area per unit mass of the propellant is a key characteristic for determining the overall burn rate and hence performance. Grain configuration also influences temperature sensitivity. Additives such as stabilizers and deterrents are added at different stages of the manufacturing process (blending or extrusion); concentration of these additives are mostly on the outside surfaces. Changes to the concentration gradient changes burn rates.

Ken
 
ken...i had read that burn rate was related to surface area and thus kernel shape and size.....so yep i agree ohh and surface coating too)

mike in co
 
Last edited by a moderator:
I don't know about the shape thing and burning rate. Ever looked at 133 under a magnifying glass. No two pieces are even the same size, some are not even the same shape.........jackie
 
Jackie the 133 does not throw too well from my Culver. I was trying to figure out some way to make it even smaller so I wouldnt have the hard cut all the time.
What do you think?
 
jackie schmidt said:
I don't know about the shape thing and burning rate. Ever looked at 133 under a magnifying glass. No two pieces are even the same size, some are not even the same shape.........jackie
Click to expand...

I hear time and time again that Vihtavuori Single Base are blended to final burn rate....... Not sure if it's true or not... 135 has similar variable size and shapes but not a erratic.. 140 too...
133 is erratic for sure.

The 8208 family has among the most consistent kernal shape / size of all single base powders .. Part of it's unique SHOOTING ability me thinks.

cale
 
Jackie

I am not sure either but I think the powder making business is both science and art. Powder is blended, recycled, mixed, sieved and screened. No so easy to be exact and, somewhat represented by what we see with the differences from lot to lot. When it comes to Web Size - The distance of travel of a burning surface in a propellant grain to give complete combustion – and will have to do as much with its formulation and composition density as actual dimensional size. Late in the process it is tumbled and polishing agents are added; resulting in a more uniform burning and or performance.

Ken
 
Vern,
If you look in the thread, on this board, about the June results from Visalia, you will see a picture, and account of a very small group, shot with a sporter in a five shot unlimited match. If you look at the details, you will see that it was shot with 322. 133 is not a requirement, but if you must, all I can say is that Jerry Hensler, (who has done more work experimenting with and modifying powder measures than any one I have ever heard of) finally gave up and started using a Chargemaster. Beyond that, I suggest that you spend a lot of time practicing throwing charges, and weighing them with an electronic scale that reads to .02 gr., and while you are at it, think out of the box.
Boyd
 
You must log in or register to reply here.
Back
Top