April 2026 (2) - Flipbook - Page 32
Do You Need a 900
yard Load?
By Kenny Wasserburger
The Phase
The concept of an issue occurring
down range at around 900 yards.
This concept sprang from many
observations, over these past
29 years of long range competition with the BPTR. The issue
happens occasionally, yet it not
always. This of course is puzzling
from the shooter’s standpoint.
In early November 2024 I decided to make a serious investigation into this perceived phenomenon. I launched a thread on the
Shiloh forum. Initially I was met
with some resistance in my 昀椀rst
few posts on the subject. I was
fortunate enough, or better yet
relieved, to soon 昀椀nd out that it
was not just anecdotal observations, on my part. Through my
extensive research I soon found
that empirical evidence exists
of this phenomenon. Enough to
back up those perceptions, that
it is actually a thing, ongoing at
roughly 900 yards. There is a
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physical point, in our bullet’s trajectory where the
bullet speed drops from
the transonic range to
the subsonic range. That
is an indisputable fact of
physics. In modern ballistic terminology this is
referred to as the Magnus
moment. Our bullets, unlike modern ones, spend
the majority of their 昀氀ight
time in the transonic speed zone.
Around 1.3 to .8 Mach, which is a
term for projectile speeds in relation to that of the speed of sound.
At .8 Mach the bullet’s speed
drops into the subsonic speed
range. This occurs at around
900 fps (Feet per Second) bullet
speed. This point of inception is
highly dependent on temperature, humidity, and altitude,
plus barometric pressure. This
interaction or phenomenon, has
a speci昀椀c point where unpredictable e昀昀ects on the bullet’s trajectory can or will occur.
The PIP.
I had coined a term for the phenomenon, calling it the phase
inception point, aka the PIP for
short. In order to further explore
this for the BPTR I dusted o昀昀 my
trusty LabRadar Unit. For those
that are not aware of these radar
type chronographs, they have capabilities far beyond most standard screen chronographs. This
includes the very handy Garmin
units.
The reason for the using a radar
chronograph is that it can measure our 45 caliber bullet velocities out to about 200 yards in
favorable conditions. Often the
Wyoming wind doesn’t cooperate with our testing, however
readings at the muzzle and out
to 50 yards are very repeatable.
One asks why bother with an
accurate down range velocity,
what purpose does this serve?
The answer is to provide an
accurate Ballistic Coe昀케cient, or
BC. Once su昀케cient accurate data
was gathered we averaged the
results. Using the free JBM ballistics website, one can input the
velocities avg at the muzzle and
50 yards out, and it will calculate
a BC. The G1 Drag pro昀椀le is also
imputed into the calculator. A
very accurate BC is calculated via
this method. The labradar allows
us to have our own personal ballistics laboratory to gather these
measurements and critical data.
This data in turn can be used
then to generate valuable information. With one’s own personal ballistics laboratory at their
disposal in the labradar unit.
Most will ask Why? Would one
go through all these steps to generate this data. This is necessary
to give us BPTR shooters a better
understanding what we deal with
down range. Another JBM calculator is then inputed with this
April, 2026 - Issue #2
