What is the best all around rifle cartridge for a
large bore rifle? Also, what is the best test to determine that top
candidate? I would like to expand on a statement by Finn Aagaard
(Safari Rifles, Craig Boddington – Pg 378), where he says, "I
have never been able to detect any difference in the field on game,
between the .458 and .500/.450, .465, .470, or even the .500 Nitro
Express."
OK, maybe just another man’s opinion, but it is a
concept I combined with another author’s remarks declaring that a
bullet with the sectional density of .300 and a starting velocity
near 2000 fps or better, is needed to take down an elephant (Richard
Harland, NDLOVO The Art of Hunting the African Elephant, page 380).
So, I came up with the following theory.
Sectional Density times Velocity, for solid rounds,
appears to be the universal equation that levels the playing field
and removes all the voodoo, folklore, and literary romance from the
discussion. This value to me is the clearest penetration calculation
check of a caliber encompassing mass, cross sectional area, and
velocity.
This value stops short of John Taylor’s theory in
creating a KO factor.
Taylor’s factor is Bullet Mass in grains, Velocity
in feet per second and Bullet Diameter in inches multiplied together
then divided by 7000. A 30-06 has numbers near 21, 375 H&H around
41, 416 Rigby at 57 and a 458 Win Mag comes in at 70.
These values are of a general nature (bullet weights
and velocity) to indicate the step increase in the cartridge’s power
levels, and show the brilliance of John Taylor in his time.
His
life experience, in taking large numbers of game and being able to
correlate his values to his field observations, is something few
have attempted. In this case, the bullet diameter is a plus as a
larger bore rifle firing an equivalent bullet weight at the same
velocity is a better "thumper" based on Taylor’s calculation.
Regarding this analysis of penetration, the opposite
is true with a bullet of higher sectional density hence a smaller
diameter for the same given weight and velocity will provide better
penetration results.
Listed below is a small sampling I have put together
comparing some of the common African rounds with some general
velocities and bullet weights.
The
benchmark I use is the 470 Nitro as my years of reading found no
abusive language and this caliber found in the same sentence; it is
a saint.
The Section Density times Velocity target value is
682.
A comparison of the numbers supports Mr. Aagaard
statement with most rounds equaling or exceeding 682. I also looked
at 458 Win Mag in detail by dropping the velocity and found I could
match the 470 Nitro at 2000 fps and match the 505 Gibbs penetration
factor at 1950 fps.
I started with the .338 caliber as I have come
across a number of articles with the 338 Win Mag being used on Lion
and Cape Buffalo very successfully and I personally own one. Top
honors go to the 375 H&H, 416 Rigby, and 458 Lott - showing why they
can take large game at almost any angle.
The winner is the 338 Win Mag based on this
comparison, a true scalpel in the hands of a professional using the
275 Tungsten African Grand Slam bullets. Unfortunately, Speer no
longer makes these.
I will concede that the 338 lacks the frontal area
of the 375+ calibers (even the 375 is the questionable at times) to
be regarded as any type of charge stopper, but with proper shot
placement dispatch anything it is pointed at.
I was also able to locate a wonderful set of test
data, "Comparing the Big Bores" by Dave Estergaard (
