Ballistic Coefficients (BC) are a crucial factor in determining the accuracy, stability, and range of a projectile. It is a measure of a projectile’s ability to overcome air resistance and maintain its velocity as it travels through the air. In this KIR Ammo blog post, we will discuss what ballistic coefficients are, how they are calculated, which bullets have the highest BC. Before going further, you might want to take a look at our Ballistics 101 page. When you purchase ammunition from KIR Ammo, take into account the “BC” if serious accuracy is important for your shooting needs.
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What is Ballistic Coefficient?
Ballistic coefficient (BC) is a numerical value that represents the ability of a bullet or other projectile to maintain its velocity as it travels through the air. It is a measure of the aerodynamic efficiency of the projectile, with higher values indicating greater efficiency. The BC is affected by several factors such as the projectile’s shape, weight, and sectional density.
The Importance of Ballistic Coefficients:
The ballistic coefficient is an important factor in determining the accuracy, stability, and range of a projectile. A high ballistic coefficient means that a projectile can maintain its velocity and trajectory for a longer distance, leading to improved accuracy and range. The BC also affects the projectile’s stability in flight, as a higher BC generally means the projectile is less susceptible to wind drift and other environmental factors. Let’s say you are planning to take a long-range shot, but the wind is gusting unpredictably. By using a bullet with a high ballistic coefficient, you can reduce the impact of the wind on your shot and maintain greater accuracy and precision. This can help you make more consistent shots and improve your marksmanship skills overall.
Have you ever heard of the term “Bullet Drop”? This term is related to ballistic coefficients. Bullet drop refers to the amount of vertical drop that occurs as a bullet travels through the air due to the effects of gravity. The amount of bullet drop depends on several factors, including the ballistic coefficient of the bullet, the muzzle velocity of the firearm, the range of the shot, and the angle of the shot.
A bullet with a higher ballistic coefficient will experience less bullet drop because it can maintain its velocity and trajectory better than a bullet with a lower ballistic coefficient. Therefore, the ballistic coefficient of a bullet is an important factor to consider when attempting to reduce bullet drop and improve accuracy at longer ranges.
Calculating Ballistic Coefficient
There are various mathematical equations that can be used to calculate the ballistic coefficient of a projectile. One of the most widely used is the G1 model, which is based on a standard reference projectile shape. The G1 model assumes that the projectile is a long, streamlined shape with a pointed nose and a flat base.
The formula for calculating the G1 ballistic coefficient is:
BC = (SD / C) x 10.935
Where: BC = Ballistic Coefficient SD / Sectional Density C x Drag Coefficient
The sectional density (SD) is calculated by dividing the weight of the projectile in pounds by the square of the diameter in inches. The drag coefficient (C) is a value that represents the resistance of the air to the projectile’s motion and varies depending on the projectile’s shape, velocity, and other factors.
Soo… Do I want a High or Low Ballistic Coefficient?
It is preferable to have a high ballistic coefficient because it indicates that the projectile has a more streamlined shape, higher sectional density, and lower drag, which enables it to maintain its velocity better and travel further with less drop and wind drift. A high ballistic coefficient bullet will be more accurate, have a flatter trajectory, and retain more energy at longer ranges than a bullet with a lower ballistic coefficient.
Bullets with High Ballistic Coefficients
Bullets with a high sectional density, streamlined shape, and low drag have the highest ballistic coefficients. Here are some examples of bullets with high ballistic coefficients:
- Boat-tail bullets: These bullets have a tapered base that reduces drag and improves stability, making them highly efficient in flight. Examples include the Hornady ELD-X and Berger VLD Hunting bullets.
- Very Low Drag (VLD) bullets: These bullets are designed with a sharp, angled nose that minimizes drag and maximizes the efficiency of the bullet in flight. Examples include the Berger VLD and Sierra MatchKing bullets.
- Polymer-tipped bullets: These bullets have a pointed tip made of a polymer material that reduces drag and improves the bullet’s ballistic coefficient. Examples include the Nosler AccuBond Long Range and Hornady ELD Match bullets.
- Monolithic bullets: These are solid bullets made of a single material, such as copper or brass, and have a high sectional density and streamlined shape, making them highly efficient in flight. Examples include the Barnes TSX and Hornady GMX bullets.
In What Situations Might BC not Matter?
Ballistic coefficients may not matter as much in situations where the range of the shot is relatively short or where the environmental factors such as wind, temperature, and altitude are minimal. For example, when hunting at close range or shooting in an indoor range, the impact of environmental factors on the projectile’s flight trajectory may be negligible, and other factors such as bullet weight or type may be more important to consider.
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