an available .com name. A name that is both relevant to the subject and available.
That being said, 30-06 ballistics will discuss more than ballistics. The following
excerpt is for those of you who came for ballistics information.
30-06 Ballistic Basics
Interior ballistics- this area is important after ignition but before the bullet exits the
barrel of the gun. Important variables that occur during this time are: pressure burn
rate temperature, expansion ratio, acceleration.
Exterior ballistics-this area of study occurs immediately after the bullet leaves the barrel and as the bullet is flying
through the air, but before it reaches the target. During this time the flight of the bullet is effected by physical forces
such as air resistance and gravity. These forces cause negative acceleration and downward path curvature.
Terminal ballistics- this area occurs when the bullet strikes an object. How the object and bullet affect each other.
Understanding interior ballistics is important especially if you are a reloader, ammunition and firearm designers.
If you are a long range shooter the area of exterior ballistics would be of great interest to you. Terminal ballistics
is especially important to hunters, law enforcement, and military.
30-06 ballistics – a few important factors
Sectional density (SD) The greater a bullets SD the easier or more efficiently the bullet will overcome
resistance. In our case, air resistance and resistance produced as a bullet penetrates an object. SD is not
the only parameter at play but it is important.
Sectional density of bullet = M/d^2 (squared, ^ means to the power of)
M = Mass of the bullet, kg or lb.
d squared = diameter of the bullets caliber (inches or or meter).
Notice the diameter in the formula is squared. This means a small increases and decreases in diameter will have
huge effects on SD. A needle has a much greater SD than a silver dollar. Meaning the needle will more
efficiently overcome both air resistance and resistance produced when penetrating an object.
Form Factor (i) – This is another term found in load manuals. The form factor of a bullet equals the drag of
the bullet (CB) divided by a standard drag (CG). In the projectile model the standard drag equals 0.5191.
Form Factor (i) = CB/CG.
Why discuss sectional density (SD) and form factor (i)?
Notice the equation below:
Ballistic coefficient (BC) = SD/i
When you know have SD and i you can then calculate the ballistic coefficient.
Ballistic coefficient – is a measure of how efficiently a bullet works to overcome air resistance. A fired
bullet moves through the air accelerating to a certain velocity. Air resistance is the major force working
on the bullet in the opposite direction. Air resistance will eventually win, causing negative acceleration
and a decrease in velocity.
The higher the bullets ballistic coefficient, the lower the negative acceleration.
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