|USING VIBRATION TO SETTLE & COMPACT
By Wayne McLerran
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 droptube. 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 work 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
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 trend 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.
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 1.5
Fg 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,