Using Vibration to Settle & Compact Black Powder
By Wayne McLerran
10/22/20
For a couple of decades, I’ve been using what I refer to as my improvised semi-automated black powder cartridge rifle (BPCR) reloading setup, consisting of an older RCBS powder dispenser setting on the top of a tall stand and positioned above a long drop tube. The drop tube is centered over a case setting on the platen of an RCBS digital scale at the bottom of the stand. The dispenser and scale were modified to use a fiber optics cable for communication. The dispenser can be quickly programmed to trickle-drop any charge quantity to within 0.1gr into the top of the drop tube. This setup is especially useful when working up new load configurations.
More recently some black powder reloaders have designed a similar setup using modern RCBS or similar equipment requiring a custom flat wire cable for the dispenser-to-scale communication link. But knowing what I know now I would not recommend this approach, even to existing or new shooters that like to “tinker” due to simpler methods being available. In fact, based on recent experimenting detailed below, I will go so far as to state that the time-honored technique of using a drop tube is not necessary.
As the title of this article suggests, for some time now I’ve been using vibration to settle and help compact the powder. It’s not a new technique and has been used by some shooters for many years, but until recently I’d never tried it. Once the powder is dumped into the case a vibrating device is held against the case to settle the powder. A vibrating tooth brush and a hand-held engraving tool were used (Photo 1). Both works equally as well as long as the flat side of the shaft on the tooth brush unit was held against the case. Cheap electric tooth brushes can be purchased for less than $10. Amazon has several low-cost hand-held engraving tools for around $10 to $20. The cheapest one you can find will work great for this application. No doubt there are other vibrating devices that will also do the job. BTW, the sloped end of the engraving tool is pressed against the case, not sharply pointed tip, or ground the sharp point flat.
Once the cases are charged and setting in the loading block, press vibrator against each case and watch the powder settle to a lower level. It only takes a second or two per case. Then continue the rest of your standard loading process.
I setup a quick experiment to visually display the differences between just dumping the powder in the case vs. using a drop tube and vibration. See Photo 2. Since the only clear tubes I had on hand were larger (0.150” inside diameter) than a .45-70 case, 150grs of Swiss 1.5Fg was used. The powder in the center tube was slowly dropped through a 28” drop tube. The powder in the right tube was dumped in then vibrated with the engraving tool. In this example the difference between the dumped and drop-tube powder height was approximately 1/8” (0.125”), equal to about 18grs of powder. The difference is less in an actual .45-70 case. Although you can possibly see a slight difference in the powder height of the drop tube and vibration samples, I’m unable to detect a difference when using 55 to 70grs in an actual cartridge.
BTW, modeling clay was used to hold the rounded bottom tubes in place. The ruler is to indicate the tube heights were the same, and a small section was copied and rotated to display the difference in powder heights. The tube volumes were also measured to ensure all were equal.
I’ve been unable to detect a difference in accuracy when shooting in ideal conditions with ammo loaded using either the drop tube setup or vibration method. And no overall trejnd has been detected, good or bad, in my resulting silhouette match scores. Although I’ve proven to myself that vibration works just as well as a drop tube to settle and compact the powder, I will continue to use the customized RCBS setup with a drop tube when working up various loads for a new bullet or rifle. Once the best powder charge is determined, a manual operated powder measure will be used, followed with vibration to settle and compact the powder.
As a final note to new BPCR shooters, if the automated setup had not been constructed a couple of years after “getting” into BPCR, I most likely would have switched to measuring by volume and tried vibration a long time ago. Although I enjoy casting and loading about as much as shooting, measuring each powder charge then slowing trickling it through a drop tube by hand does not fit into my definition of fun.
Update 10/22/20
The above details were based on using powder from 3 cases of 2012 vintage Swiss 1.5Fg powder which I finally “burned through” and turned out to be significantly denser than the more recent lots of Swiss 1.5Fg. Hence there was little difference in using a drop tube vs. vibration. Not so with some 2016 (lot # 18-01-2016) powder I just started using. Using the newer “fluffier” powder resulted in a significant difference between settling the powder with a drop tube vs. vibration. I just finished comparing the two techniques when loading 55.5grs in a .40-65 case. Loading the same 10 cases using each technique resulted in an average difference of 0.040”. I.e., the level of the powder in the drop-tube cases was 0.040” lower than in the cases with the powder settled using vibration, which resulted in a compression reduction of 0.040” or equivalent to about 1.5grs of 1.5Fg powder in a .40 caliber case.
By the way, all being equal (same wad, same bullet, same COAL, etc.), with the exception of the old vs. the new powder, 55.5grs with the old 2012 powder resulted in an average compression of 0.085” while 0.165” of compression is required with the newer 2016 powder. Since I have a case of the 2016 powder, I’m considering mixing 3Fg with it to reduce the compression amount and also using a drop tube rather than vibration to help in reducing the required compression. I have found that Swiss works better for me if the compression is limited to 0.100” or less.
For some more density comparisons, I also have several pounds of 2017 Swiss 1.5Fg (lot # 27-11-2017) and ran a compression comparison with 55.5grs using the drop tube. It’s even fluffier than the 2016 stuff and required 0.185” of compression. And just for “kicks”, using a drop tube with 55.5grs of Swiss 3Fg (lot # 30-04-2018) resulted in 0.152” of compression which surprised me. I expected the compression to be significantly less. Finally, I checked some 3Fg (lot # 15-04-2019) resulting in 0.079” of compression. Obviously the 2019 3Fg is a good bit denser than the 2018 3Fg.
Should those of you reading this wish to make a similar comparison between different lots, be sure to use the same case to eliminate differences in volume capacity. I did use 10 separate cases that were sorted and selected by weight to make the earlier comparison of using a drop tube vs. vibration, but the weight spread was no more than 0.2grs between cases. Regardless, for a more precise test, the same case was used several times with each powder to check the noted relative compression of several lots and powder granulations.
Wishing you great shooting,
Wayne