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The Bigotry of Ballistic Coefficients 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 .458, 350 grain, Barnes "X" Bullet: 1:28.4 Restricted to 1 MOA verified bullets: Worst BC on list: 250 grain XTP @ .146 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 grain XTP = 182 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 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 grain Barnes Original for the 300 grain 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 grain 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 grain 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 knockdown power at all ranges. That's the real crux of this biscuit. |
Copyright 2005, 2012 by Randy Wakeman. All rights reserved.
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