Shooter's Glossary: Ballistic Coefficient

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Shooter's Glossary: Ballistic Coefficient

Ballistic Coefficient (BC) is a term frequently used in the realms of firearms, ammunition, and the shooting sports.

It is a measurement of how efficiently a bullet defeats air resistance as it pushes through our atmosphere.

A high ballistic coefficient is good, it means the projectile has low-drag and will travel quickly for longer distances than a projectile with a low ballistic coefficient.

When thinking about ballistic coefficient, the main factors are a projectile’s mass, diameter, and drag coefficient.

Ballistic Coefficient

Here's a comprehensive description:

Definition
The Ballistic Coefficient (BC) is a number that quantifies a bullet's aerodynamic efficiency. Essentially, it's a measure of how well a bullet overcomes air resistance during flight.

Calculation and Factors

BC is derived from a formula that takes into account the bullet's shape, weight, diameter, and its ability to maintain velocity. The higher the BC, the better the bullet is at retaining its speed and resisting wind deflection.

Factors like the bullet's shape (e.g., boat tail, spitzer, round nose), weight, and size all influence its BC.

Purpose and Benefits

Understanding BC is vital for long-range shooting. A bullet with a higher BC will be affected less by wind and will generally have a flatter trajectory, leading to more consistent accuracy.

BC values help shooters and hunters select the best ammunition for their intended use.

High BC bullets are often chosen for long-range target shooting or hunting in open terrain, where wind and long distances can greatly influence a bullet's path.

BC in Ammunition Choice

Ammunition manufacturers often provide BC values for their bullets, allowing shooters to make informed choices based on their shooting needs.

Advanced ballistic calculators utilize BC values, along with other inputs like muzzle velocity, atmospheric conditions, and rifle characteristics, to help shooters predict bullet trajectory and optimize accuracy.

Dynamic vs. Static BC

It's worth noting that BC isn't always a fixed value. As bullets slow down, their BC can change.

Some advanced ballisticians and long-range shooters work with "dynamic BCs" that account for these changes over different velocity bands.

Ballistic Coefficient Chart

In essence, the Ballistic Coefficient is an indispensable tool in the shooter's arsenal, providing a scientific basis for understanding and predicting bullet performance under varying conditions.

Knowing and understanding BC can be the difference between a hit or a miss, especially at longer ranges.