Ballistics & bullet drop, hollywood style???

I am not sure one guy's nonsense should reflect on the overall training. I doubt that academy teaches 1000 yard rifle shooting, so what a bullet does at that range is irrelevant to their training program.

But the fact is that the kind of "rainbow" arc seen in those drawings is misleading. In a scale drawing, with the width of the screen 1000 yards, that huge peak would be the thickness of a pencil lead.

Jim
 
I doubt that academy teaches 1000 yard rifle shooting,
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The speaker was responsible for teaching the lead actor to shoot out to 1,000 yards on what he referred to as an "Indexed range" & 1100 yards on an "unindexed range". I assume he's referring to ranges with known & unknown target distances.
Based on that I'm pretty sure they do indeed teach that kind of distance shooting.
 
It's easy to use ballistics software and figure out what the angle of fall bullets have at any target range. I've done so for the .308 Win. and at 1000 yards, bullets drop about 1 inch for every yard of downrange travel with their 1.6 degree angle of fall.

Note also, that on M1's and M14's, a zero at 1000 yards means a come up from a 200 yard zero of some 37 or 38 clicks is needed. When added to the 5 or 6 clicks up from boresight to zero at 200 yards, that means 43 or so clicks up for a 1000 yard zero. Each click's about 1 MOA and 43 MOA at 1000 yards equates to about 430 inches of drop for the bullet. That's about 36 feet.

Note also that the maximum ordinate (bullet height above line of sight) is about one-third of their total drop at the target. Here's some examles:

.308 Win, 1000 yard zero, max ord equals about 11 feet; for 600 yard zero it's about 3 feet.

.300 Win Mag, 1000 yard zero, max ord equals about 8 feet; for 600 yard zero it's about 2 feet.

At any horizontal target range, the angle of fall's much greater than the angle of departure (up angle the bore's at when firing the bullet). Only in a vacuum will they be the same.

The nose of the bullet does not maintain the same attitude it had when it left the barrel. . .; contrary to the popular myth that it does. The bullet's spin axis always stays parallel to the trajectory curve just like a passed football from a quarterback enroute to the receiver; they both nose over so their drag stays fairly constant. If bullets stayed "nose up," then their BC's would go horibbly low in the last part of their flight. Can you imagine an artillery projectile flying through the air and being accurate in its downward 45 degree path if it had the 45 degree up angle it was fired at and was 90 degrees to the trajectory path? Yikes, folks, go figure this out!!!!!!!!!!! Small arms ammo's no different.

In real world stuff, consider the .308 Win. shooting 155's out at 3000 fps and zeroed at 900 yards in a Palma match. About 7 MOA comeup's needed to zero at 1000 yards. So, the bullet's down about 70 inches 100 yards past its place at 900 yards. Straight line, that's about 1.1 degrees down, but the trajectory's curved so the bullets angling down at about 1.6 degrees when its at 1000 yards. The rear sight's up about .5 degrees above boresight for a 1000-yard zero.
 
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Can you imagine an artillery projectile flying through the air and being accurate in its downward 45 degree path if it had the 45 degree up angle it was fired at and was 90 degrees to the trajectory path? Yikes, folks, go figure this out!!
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I imagine it would curve like a sliced golf ball.
 
When spotting the fall of 5" gun projectiles aboard USN destroyers in the late '50's, I could watch them go out, up then nose over going down onto surface targets. They were easy to see looking through a 24X optical rangefinder.
 
If the rifling twist is too fast, the bullet will resist reorienting itself to the curved trajectory. This is an overstabilized bullet. Overstabilizing a bullet matters little at point blank range but is undesirable for long range shooting.

Ideally, you want just enough twist to stabilize the bullet and no more.
 
B.L.E.'s point about overstabilizing bullets is a good one. But that rarely, if ever, happens with small arms. One could get a 1:7 twist barrel chambered for the .25-.378 wildcat and shoot 90 grain bullets fast enough to do that, but why?
 
B.L.E.'s point about overstabilizing bullets is a good one. But that rarely, if ever, happens with small arms.
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I have wondered about that, in particular to .224 52 Gr SMK from a 1:8 twist .223.

I never shot them at a range where it would matter, but the thought did cross my mind.
 
I can't believe you guys are still talking about this one.:rolleyes:

Anyway, assuming the maximum height above line of sight for a rifle zeroed at 1,000 yds (3,000 feet) is 18 feet, that is less than one degree. Stop and think about it: you use a 20 minute base (1/3 of 1 degree!!) to be able to sight the rifle in, so it can't be coming down at anything like 45 degrees. Sure, the trajectory in the last 100 yds is pretty steep, but it's nowhere near straight down.
 
Scorch's example's exploded below.....

175-gr. bullet with a G1BC of .500 leaves at 2150 fps.

At a departure angle of about 1.1 degrees up, it'll be about 18 feet (216 inches) high traveling horizontally 560 yards down range; a point about .6 degrees up from the horizontal at the muzzle.

At 990 yards, the bullet's about 10.7 inches above the line of sight then takes about a 1.8 degree angle of fall to the 1000 yard target point of aim.
 
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