April 2026 (2) - Flipbook - Page 36
maintaining stability further
out for our BPTR’s. Again this
is something I subscribe too, 16
twist 45’s and 14 twist 40’s. What
I used to think, ie Speeding our
bullet up, has proven to counter
productive, in actual Labradar
testing.
In My Opinion, it is utter hubris
to consider what the old timers
were doing or not doing. Why?
Their period of extensive use was
less than 10 years. Our own
golden age of BPTR Long
Range has now exceeded
that by almost 3 times as
long a period of time. They
had far less practical time
investigating the long range
mechanics as we have.
Signi昀椀cance in Unique
Cases: Litz notes an exception in the case of transonic
black powder ballistics,
where dynamic stability can
rely heavily on the Magnus
moment. In such cases,
the e昀昀ect is much harder
to calculate and predict,
often requiring real-world
testing. Now who would
have thought that? This is
the 昀椀rst time in actual Print
that I have seen reference
to this! Notice the part: the
e昀昀ect is much harder to calculate and predict, often requiring
real-world testing. Here is where
a few folks need to read this then
again. The PIP or Phase inception Point, isn’t some imaginary
friend or nemesis, that I dreamed
up. It’s actual physics of any
Spin-stabilized bullet no mater
the composition of said bullet.
In modern bullet terms this is
often referred to as the Magus
Moment.
Distinction from Crosswind Ef36
fects: Litz clari昀椀es that the common illustration of the Magnus
e昀昀ect in a crosswind (showing
lift/drop as in a curveball) is not
entirely relevant for a bullet’s
trajectory. Instead, a bullet’s nose
tends to point into the oncoming
air (weathercocking), and the
resulting vertical de昀氀ection from
a crosswind is primarily due to
aerodynamic jump, not the Magnus e昀昀ect.
Complex Modeling: The Magnus
and manageable component for
standard long-range shooting,
with the exception of speci昀椀c,
niche scenarios like certain transonic or highly unstable projectiles. BPCR!! Transonic.
There appears to be some serious
misconceptions about our bullet
speeds, among our fellow BPTR
shooters. Some even stating that
our bullets are subsonic by 800
yards. This couldn’t be further
from the Truth. Ballistic
modeling using my 1357
Fps load shows, @900
yards a velocity of 911.6
Fps .802 Mach. @1000
yards a velocity of 888 fps
.781 Mach!
In summary, while present in all spin-stabilized
bullets, the Magnus or
PIP moment is particularly relevant to BPCR
shooting. Because the
sport involves 昀椀ring
low-velocity projectiles
over exceptionally long
distances. Making otherwise negligible e昀昀ects
in modern long range,
yet a factor in achieving
pinpoint accuracy for the
BPTR shooter.
force and moment involve complex boundary layer interactions
that are di昀케cult to predict solely
through theory. This complexity is why Litz often emphasizes
live-昀椀re testing and the use of
6-degree-of-freedom (6-DOF)
modeling, which incorporates
real-world data, for the most
accurate results.
In summary, Litz views the Magnus moment as a real, measurable aspect of external ballistics,
but one that is generally a small
Moving forward in my somewhat
amateur attempts to better understand the down range ballistics of our bullets. I have recently
secured Bryan Litz’s two volume
set “Modern Advancements in
Long Range Shooting.” There is
a plethora of information in this
two volume set, sharing concepts
that further one’s understanding of what is happening, down
range in long range ballistics.
Currently I have just ordered
volume III.
April, 2026 - Issue #2
