Sectional Density and Muzzleloading Projectiles
Sectional
density is an important component of a bullet's ability to penetrate,
and destroy the vital organs of a game animal requisite for a quick
kill.
Chuck Hawks clearly, concisely describes and compares sectional
density here: http://www.chuckhawks.com/sd.htm
so I'll not duplicate what Chuck has already set forth so extemely
well.
Dr. Martin
Fackler, the world's foremost expert on wounding ballistics has
documented the better wounding of longer, heavier bullets. The FBI
Quantico study has done the same, showing that longer bullets produce
greater wounds and have greater lethality. The longer, heaver bullets
naturally have greater sectional densities as well. Along with the
better sectional density for a specific bullet design comes less
velocity erosion with the automatically higher ballistic coefficient,
and perhaps more important to the muzzleloading hunter: less wind
drift.
It is not
that the worst sectional density muzzleloading bullets have not
harvested game; even the ballistically challenged round ball has
taken its fair share. Under ideal circumstances, a broad side or
honey hole shot, fragile, easily frangible bullets do work. When
the angles are less than perfect, and raking shots or through the
chest shots are needed-- poor sectional density muzzleloading bullets
have failed. By fail, I mean
fail to drop the animal quickly, resulting in either a long tracking
attempt or lost game. I've witnessed too much of this, and a commonality
has been bullets with poor sectional density. Sectional density
is important in rifle bullets, handgun bullets, and muzzleloading
rifles are in no way exempt from the fundamental results from good
(or poor) sectional density projectiles documented over the
decades. When the game gets larger and tougher, sectional density
becomes even more vital.
A muzzleloading
projectile with a section density below .200 is deficient for the
more demanding shots on thin-skinned game (CXP2 class), and for
even a greater variety of shots on heavier game animals(CXP3 class).
I'll be specific as to what bullets look borderline; of course you
are the final judge of how, where, and why you might take a specific
shot at an individual game animal.
POOR
.40 caliber
Hornady 200 grain SST: SD = .179
.452 caliber Hornady 250 grain SST: SD = .175
.490 caliber (".50 cal. Roundball") 177 grain SD = .105
.50 caliber (.499) Powerbelt 245 grain: SD = .141
.50 caliber (.499) Powerbelt 295 grain: SD = .169
.50 caliber (.499) Powerbelt 348 grain: SD = .181
.535 caliber (.54 cal. Roundball) 230 grain: SD = .115
This is a 250
grain Hornady SST was recovered from a 75 yard broadside
shot placed behind the shoulder into a Michigan 4-point at 70 yards,
pushed by 90 grains of Pyrodex. Despite the excellent shot placement,
the 135 lb. field dressed weight buck still traveled over
75 yards before finally piling up. 
In
areas requiring instant anchor for confident quick game recovery,
this bullet is a very poor choice. In fact, more deer were lost
in a specific coastal carolina hunting camp with SST's in ONE year
than in in the prior ten years with 300 grain XTP's. Failure to
kill quickly, failure to recover animals, and poor sectional density
go hand in hand way, way too often.
GOOD
.458 Barnes
Original 300 grain: SD = .204
.451 Barnes Spitfire 285 grain: SD = .200
.451 Barnes MZ-Expander 300 grain: SD = .211
.451 Buffalo SSB 375 grain: SD = .263
.452 Hornady XTP 300 grain: SD = .210
.458 Hornady HP #4500 300 grain: SD = .204
.50 caliber (.499) Powerbelt 405 grain: SD = .232
There are other
considerations beyond sectional density you might wish to evaluate.
Pure lead pancakes at low velocities, inhibiting penetration. This
makes the lighter Powerbelts which are nothing but soft lead, and
lead roundballs penetrate even less than their dismal sectional
densities might indicate. The lead 375 grain Buffalo SSB is far
more likely to get you where you need to be in less than ideal hunting
circumstances.
Flipside, Barnes
all-copper bullets by virtue of their 100% weight retention potential,
have been proven to out-penetrate thin-jacket bullets by a large
margin. So, though a 245 grain .451 Barnes Spitfire has a sectional
density of .172, it penetrates like a substantially heavier bullet.
The same is true for the new .193 SD Barnes .451 275 grain XPB,
which has already proven itself by out-penetrating its 300 grain
jacketed competition.
This 245 grain
Barnes Spitfire was placed into the chest, a head on shot by Bill
Konway of Indiana using 150 gr. of Triple 7. The bullet traveled
the entire length of the animal, exited near the groin, re-entered
the inside of the hind leg, and finally came to rest at the back
of the hind leg. The deer traveled zero yards; you can see both
the excellent expansion and 100% weight retention. This was an instant
kill with the all-copper Barnes Spitfire, but a very risky shot
with a low sectional density conventional bullet on deer-- even
more ill-advised on larger game.
Use
of bullets with sufficient section density enable you to quickly
kill and retrieve big game that otherwise would be lost in dense
cover or with raking shots. It is something that Elmer Keith, Jack
O'Connor, Charles Askins, the FBI-Quantico, Dr. Martin Fackler,
Ballistics Engineer Paul Von Rosenburg, Dr. Gary "Doc"
White, and Duncan MacPherson have all universally embraced in various
ways.
A
few personal examples:
Manitoba
caribou, .451 340 gr. lead bullet @ 157 yards SD= .239: Zero Steps.
Kuujjuaq,
Northern Quebec caribou, .277 150 gr. PG @ 220 yards SD= .279: Zero
Steps.
Newfoundland
Bull Moose, .277 150 gr. PG @ 327 yards SD= .279: Zero Steps.
Russian
Boar, Tenn., 300 gr. Barnes MZ-Expander @ 30 yards SD = .211: Two
Steps (running).
Corsican
Ram, 300 gr. Barnes MZ-Expander @ 165 yards SD = .211: Zero Steps.
Feral Hog,
deep south Texas, 300 gr. Barnes MZ-Expander @ 171 yards SD = .211:
five yards.
Pronghorn,
.277 130 gr. Nosler @ 227 yards, SD = .242: Zero Steps.
All
one-shot kills, all instant anchor, all with bullets with a sectional
density exceeding .21.
©
December, 2005 by Randy Wakeman
