Quickload Ballistics Download3/22/2021
We have chosen to compare in this example two bullets of identical caliber, weight, and sectional density fired at identical 3000 fps muzzle velocities.We are not concerned with internal ballistics, the province of the firearms engineer or powder chemist, nor with terminal ballistics, the province of the forensic pathologist or other scientific specialists.While there is no way to model the terminal behavior of all projectiles in all media at all velocities, well mention the subject briefly in the section entitled An Aside on Energy.
Trajectories for BBs, field artillery projectiles, naval gun shells, mortar rounds, and small arms bullets are all parabolic in shape. But once the projectile leaves a barrel, two other forces begin to influence its flight. Whatever its angle of departure and whatever its muzzle velocity, a shell or bullet will lose velocity from air resistance and lose height because of gravity. In Figure A (exaggerated for purposes of illustration) we show a muzzle (left) and target (right) assumed to be horizontal on the same baseline (for practical purposes the baseline is equivalent to the line of sight). The axis of the bore becomes the line of departure for a bullet leaving its muzzle. Gravity and air resistance come into play so fast that the bullet departure line is tangent to the trajectory only at the muzzle. The angle of departure (for small arms generally very small) is formed by the intersection of the line of departure and the baseline. The midrange trajectory is the bullets height above the base line halfway between the muzzle and the point of impact (here, the target). The difference between trajectories results from different angles of departure required to zero the firearm (change its point of impact) at two ranges; 100 yards and 200 yards. Trajectories fall below the baseline (line of sight) in Figure B at zeros of 100 and 200 yards respectively. Bullet trajectories beyond their point of impact are described in terms of inches of drop. Each bullet can be assigned a numerical value expressing this efficiency. The basis of this value is a ratio comparing the performance characteristics of a particular bullet against the known trajectory characteristics of a standard projectile. The ratio compares the drag of a bullet (loss of velocity caused by air resistance encountered in flight) to the drag of the standard projectile. The single exception in the entire line of Hornady Bullets is our 50 Caliber (.510 diameter) 750 grain AMAX Ultra High Coefficient. Ballistic coefficients for all Hornady Bullets were determined by computer calculations using data from test firing research performed in our 200 yard underground test range. Our ELD-X and ELD Match bullets are measured with Doppler radar at extended distances. As a practical matter, most shooters understand that bullets with a pointed shape more easily retain their velocity than round nose or flat point bullets. This can be directly observed in the amount of drop bullets of the same weight but different shapes produce at the same target range. Expressed another way, round nose and pointed bullets will require different sight adjustments to attain the same zero over the same range. If more streamlined bullets maintain their velocity better, heavier streamlined bullets of the same shape will outperform lighter bullets at the same muzzle velocity.
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