The
Bigotry of BC's
Now
that a portion of the muzzleloading community has suddenly rediscovered
ballistic coefficients, the importance placed on them has resulted
in an idolatry of BC's far in excess of what they really mean in
today's muzzleloading environment. It may be cute to denigrate a
bullet as bad due to its flight "number," but it has comparatively
little real world significance in the hunting field.
Here is a selection
of bullets that I've found to be exceedingly accurate in muzzleloaders.
As required rate of twist is contingent both on specific bullet
and muzzle velocity, there are a few muzzleloaders that may not
be able to stabilize the best flyer of the group, the 350 grain
Barnes X bullet, due to either rate of twist or more likely-the
inability to fire at 2100 fps. The 2100 fps calculated minimum rates
of barrel twist are cited here for reference.
Greenhill Rate of
Twist Required at 2100 fps
Barnes 350 gr. .458
"X" Bullet: 1:28.4
.458, 300, Barnes SpSP
.032 457010 1:33.7
.458, 300, Barnes FNSP
.032 457020 1:37.1
.458, 300, Barnes 'X'
FN 45832 1:31.0
.452, 250, Hornady HP/XTP
LC 45200 1:46.1
.452, 300, Hornady HPXTP
45230 1:39.1
.451, 300, Barnes MZ
Sabot 45130 1:32
.451, 250, Barnes MZ
Sabot 45125 1:36.4
.451, 300, Sierra JSP
FN 8830 1:37
Restricted to 1 MOA
verified bullets:
Worst
BC on list: 250 XTP @ .146 ICAO
Best BC 250 class muzzleloading bullet: 245 grain Barnes Spitfire
@ .203
Popular 300 XTP @ .180 ICAO
Best BC of 300 gr. bullets Barnes Original SpSP @ .286 ICAO
Best BC on list: 350 Barnes X @ .395 ICAO
A small amount of research
and confirmation of this data will quickly prove to anyone that
any manufacturer that makes a claim of "half the drop"
in muzzleloading land is taking extreme liberties with the truth,
and the zest to sell bullets has resulted in lies that would make
P.T. Barnum quite proud. In terms of maximum point back range at
2100 fps, the differences can be laughable bullet grain weight for
grain weight.
The industry leader in accurate ballistic coefficients, Sierra,
tries to correct the bad Ingalls table numbers based on velocity
using multiple BC's. As the operating flight characteristics of
a bullet diminish in concert with velocity increases, using one
BC number (a static BC) is bound to be inaccurate. In terms of hold
the cross-hairs on your animal let's take a look at what field performance
range increases are probable:
MPBR,
6" kill @ 2100 fps 250 XTP = 182 yards
MPBR, 6" kill @ 2100 fps 245 gr. Barnes Spitfire = 193 yards
MPBR, 6" kill @ 2100 fps 300 XTP = 190 yards
MPBR, 6" kill @ 2100 fps 300 gr. Barnes Original = 202 yards
MPBR, 6" kill @ 2100 fps 350 gr. Barnes X = 209 yards
Changing 250 class muzzleloading
projectiles will net you only about ten yards or so at the same
velocity; not much better in the 300 grain arena. A miniscule six
percent or so of increased range is all that is available to you
using similar bullet weights and velocities. You might wonder where
all the "half the drop" hyperbole came from? I sure do.
An "easy" 300 yard muzzleloader does not exist, much less
an "easy" 400 or 500 yard muzzleloader. Forty-five caliber
projectiles just cannot fly all that flat; the used-car salesman
ad-copy can't help that.
However, though the
mythical BC prowess has proved to be largely just that, and in no
way can displace the primary goals of accuracy and resultant shot
placement coupled with terminal performance, BC does make a difference
in the field. It is just not what the wild-eyed advertisements might
lead you to believe, that's all.
Far
more applicable to field performance is windage and strike energy.
Substitution of the 300 gr. Barnes Original for the 300 gr. Hornady
XTP may only give us twelve yards of range, however-- consider the
wind deflection and terminal energy advantages.
At 200 yards, with a
light 10 mph crosswind, the 300 XTP is blown over a foot away from
our crosshairs: at least 12.2 inches, likely a bit more at the stated
velocity. The Barnes Original 300 blows about 7.1 inches-over 40%
less wind deflection. That, to me, is a very real and significant
advantage.
Examining terminal energy
the 300 grain XTP hits at 200 yards with a calculated 1256 fpe.
The Barnes Original 300 grain Semi-Spitzer strikes with 1748 foot
pounds of energy, about a 40% increase. That is the "free"
benefit of the higher BC bullets-not trajectory, but greatly reduced
wind drift and higher strike energy at all ranges. Same recoil,
same powder charge, just remarkably better resistance to wind deflection
and increased shockdown power at all ranges.
That's
the real crux of this biscuit.
©
July, 2005 by Randy Wakeman
