2) External - The flight of the bullet from the muzzle to the target.
3) Terminal - What happens to the bullet after it hits the target.
Effects on trajectory
2) Drag - The slowing effect the atmosphere has on a bullet. The higher the temperature, the less dense the air. A 20 degree change equals a one min. elevation change. ie. If the temperature is 20 degrees higher than on the day you zeroed your weapon, the the bullet will travel 1 inch higher at 100 meters, 2 inches at 200 meters, 3 inches at 300 meters, etc...
3) Altitude / barometric pressure - Sense the air is thinner at higher altitudes, the air is less dense and a bullet will strike the target higher.
4) Humidity - When humidity goes up the air becomes thicker and the bullet will strike low.
5) Bullet efficiency - The bullet's ballistic coefficient will effect the accuracy. A perfect bullet would be rated at 1.00. Match bullets range from .500 to .600. The 7.62-mm bullet that the M24 uses is rated at .530.
4 Components of a rifle round 1) Primer - used to ignite the powder and create a pressure seal.
2) Case - A container / creates an airtight seal in the chamber / assists in head space / creates uniformity of bullet placement in the chamber.
3) Powder - Heat and pressure push the bullet. Three types of powder are Flake, Ball, and Extruded. Powder burns at 47,000 lbs x the number of grains (weight).
Barrel Harmonics - The flexing or whipping action of a barrel when a round is fired. Anything that touches the barrel during firing upsets these harmonics. Muzzle velocity - The speed of a bullet as it leaves the barrel, measured in feet per second. Line of sight - A straight line from the eye through the aiming device to the point of aim. Line of departure - The line defined by the bore of the rifle or the path the bullet would take without gravity. Trajectory - The path of the bullet as it travels to the target. Midrange trajectory - The highest point a bullet reaches as it travels toward the target. ( This is important to know when shooting in a wooded area, through windows or doors, and small holes or openings. Sense the bullet travels above the line of sight it is possible to hit something as the bullet rises and drops.) Bullet drop - How far a bullet drops from the line of departure to the point of aim. Time of flight - The amount of time it takes for the bullet to reach the target from the time the bullet leaves the barrel. Retained Velocity - The speed of the bullet when it reaches the target. Due to drag, the velocity will be reduced. MOA / Min. of angle - 1 MOA = 1/60th of a degree. 1 inch at 100m / 2 inch at 200m / etc..