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Old October 18, 2014, 11:01 AM   #9
sirgilligan
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Join Date: October 28, 2009
Posts: 583
Quote:
All object "drop" at the same rate. How far they drop is dependent on the time they're allowed to drop. Bullets with lower BCs shed velocity quicker, so even if they have the same MV, they shed forward velocity faster than a bullet with a high BC. Generally, within a caliber, lighter bullets have lower BCs, so they shed forward velocity quicker than a heavier bullet. Their time of flight is therefore longer, and since they're allowed to drop longer, they drop farther.
That is it. I wrote the ballistics calculator for my Gun Log apps and had to learn about ballistics. I read a lot of papers, had to get out my college physics books and re-learn what I had forgot from college.

The amount of time an object is falling is directly related to how far it will fall. If you drop a basketball from your chest it will fall to the floor in less than a second. If you climb to the top of the empire state building and drop the basketball it will take longer than a second to hit the ground. The longer something is falling the further it falls.

If I shoot a bullet at 3000 fps with a ballistics coefficient (BC) of 0.5 it will take it .33 seconds to arrive at a target 300 yards way. If the bullet it only travelling 2800 fps it take is .36 seconds to get to 300 yards, that is 3 hundredths of a second longer. During that extra 300 hundredths of a second that is nearly 3" of more drop.

Maintaining speed is what the ballistics coefficient is all about. A bullet that cuts through the air better slows down less and maintains its speed, thus reducing the time to get to the target and thus dropping less because it was falling for less time.
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