BALLISTIC COEFFICIENT BANTER

BALLISTIC COEFFICIENT BANTER

Muzzleloading hunters apparently have rediscovered ballistic coefficients, and are placing far more importance on them than they deserve. In the case of muzzleloading bullet manufacturers, they exist primarily as a marketing tool. The basis by which these flawed numbers are derived is not stated, and there is no industry standard for publishing ballistic coefficient claims. The sole exception to this is Olin Corporation, who used a 100 grain Pyrodex charge in their test rifles-- firing on their own on-site Doppler radar range, and published their BC's based on 200 yard radar-tracked averages. The rest of the bullet-sellers in the muzzleloading community are pikers by comparison. Several have a tortured system of ignoring the substantial sabot drag and resultant velocity loss right outside the muzzle, setting this aside and measuring the bullet only at extended ranges. It seems distinctly obvious that as saboted projectiles are of course fired with sabots, ignoring them while concocting an average 100 or 200 yard BC is false on its face.

The higher BC projectiles are sometimes presumed as automatically "better bullets," but that is not necessarily the case. Ballistic coefficients do not equate with accuracy, nor do they directly relate to terminal performance.

There are only a few ways by which muzzleloading projectiles can increase their ballistic coefficients. Adding mass is one approach. Use of heavier metals than lead such as gold, iridium, or osmium does the trick-- but few care for that price tag. Any metal heavier than lead has more mass, and automatically carries farther.

Going in the other direction, Barnes heat-treated copper bullets naturally have lower mass than elemental lead for a specific size. Add antimony to lead, it lightens it. Jacket a lead bullet, the BC for the exact form also goes down, as bullet jacket material, regardless whether it is made from gilding metal, copper, or other materials. In any case, BC goes up with an increase in weight. Mass can also be added by lengthening the bullet, but a longer bullet is more unstable, requiring a faster rate of spin to put it to sleep. Longer bullets also magnify any imbalances in the jacket material thickness or eccentricity, for example, and those who just can't find the accuracy with the SST vs. XTP bullets may have found one of the usual suspects. Jacket wall concentricity must be within .0002" to be considered "benchrest quality," cutting apart several common muzzleloading bullets used today can quickly reveal how surprisingly far we are from that.

Another common way is to use a spitzer bullet with a longer nose, called out as a specific bullet ogive. A longer nose indicates a longer counter-balancing shank, so again extremes can result in accuracy loss. Sometimes we seem to choose the sizzle over the bacon.

Finally, using a smaller caliber bullet for a given weight increases the BC, and that is where the big potential lies. We already have a few .40 caliber choices for .50 caliber muzzleloaders, but far too few.

Ballistic coefficients have very little meaning for sub-100 yard muzzleloading hunting, and the published numbers have even less relevance. They can be an unnecessary diversion, when the thing that matters above all else is proper shot placement.

© 2004 by Randy Wakeman

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BALLISTIC COEFFICIENT BANTER

Muzzleloading hunters apparently have rediscovered ballistic coefficients, and are placing far more importance on them than they deserve. In the case of muzzleloading bullet manufacturers, they exist primarily as a marketing tool. The basis by which these flawed numbers are derived is not stated, and there is no industry standard for publishing ballistic coefficient claims. The sole exception to this is Olin Corporation, who used a 100 grain Pyrodex charge in their test rifles-- firing on their own on-site Doppler radar range, and published their BC's based on 200 yard radar-tracked averages. The rest of the bullet-sellers in the muzzleloading community are pikers by comparison. Several have a tortured system of ignoring the substantial sabot drag and resultant velocity loss right outside the muzzle, setting this aside and measuring the bullet only at extended ranges. It seems distinctly obvious that as saboted projectiles are of course fired with sabots, ignoring them while concocting an average 100 or 200 yard BC is false on its face.

The higher BC projectiles are sometimes presumed as automatically "better bullets," but that is not necessarily the case. Ballistic coefficients do not equate with accuracy, nor do they directly relate to terminal performance.

There are only a few ways by which muzzleloading projectiles can increase their ballistic coefficients. Adding mass is one approach. Use of heavier metals than lead such as gold, iridium, or osmium does the trick-- but few care for that price tag. Any metal heavier than lead has more mass, and automatically carries farther.

Going in the other direction, Barnes heat-treated copper bullets naturally have lower mass than elemental lead for a specific size. Add antimony to lead, it lightens it. Jacket a lead bullet, the BC for the exact form also goes down, as bullet jacket material, regardless whether it is made from gilding metal, copper, or other materials. In any case, BC goes up with an increase in weight. Mass can also be added by lengthening the bullet, but a longer bullet is more unstable, requiring a faster rate of spin to put it to sleep. Longer bullets also magnify any imbalances in the jacket material thickness or eccentricity, for example, and those who just can't find the accuracy with the SST vs. XTP bullets may have found one of the usual suspects. Jacket wall concentricity must be within .0002" to be considered "benchrest quality," cutting apart several common muzzleloading bullets used today can quickly reveal how surprisingly far we are from that.

Another common way is to use a spitzer bullet with a longer nose, called out as a specific bullet ogive. A longer nose indicates a longer counter-balancing shank, so again extremes can result in accuracy loss. Sometimes we seem to choose the sizzle over the bacon.

Finally, using a smaller caliber bullet for a given weight increases the BC, and that is where the big potential lies. We already have a few .40 caliber choices for .50 caliber muzzleloaders, but far too few.

Ballistic coefficients have very little meaning for sub-100 yard muzzleloading hunting, and the published numbers have even less relevance. They can be an unnecessary diversion, when the thing that matters above all else is proper shot placement.