Disagreement about bullet drop

[MurdaJ]

Alls i knows is my rangefinder has hcd mode

[ar15barrels]

All conditions being equal for both shots, does gravity have a reduced effect on bullet drop in downward angles?

All conditions are not equal if you are comparing a level shot to an uphill or downhill shot.

Uphill and downhill shots have less gravity effect so you do not dial as much elevation to get a bullet to land on your aiming point when you are shooting uphill or downhill.

If you take your angle and look it up on this cosign chart, you will get the factor that you need to multiply against your elevation dial to account for the angle.



The chart works to about 45 degrees.
Beyond that, things get wonky because you have to account for the zeroing angle built into your level 100yd zero.

As an example, if you are shooting 30 degrees uphill or downhill at 400yds distance to target and your normal elevation dial for 400yds is 3.0 mils, you would multiply 3.0 x 0.866 and get 2.6 as your new elevation dial.
Failing to account for the angle would cause your shot to go 0.4 mils high at 30 degrees slope to 400yds.

[dwalker]

I just feed the look angle into the software and shoot where it tells me to

[ar15barrels]

I just feed the look angle into the software and shoot where it tells me to

It's good to know how to do it manually too in case your batteries die or the device overheats from being left in the sun on a hot day.
If you print this out and cutout the little chart, it's small enough to keep in your logbook and you will never be without it:

http://caprc.com/angle-of-fire.pdf

[ozarkpugs@gmail.com]

If you range a Target on a horizontal plane 300 yards and then raise that Target high enough it ranges at 400 yards and shoot it your bullet will strike as if it were 300 yards . gravity effects the bullet on a horizontal plane no matter the distance increase because of angle .


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[alpha_romeo_XV]

Are there no golfers here? A 200 yd level no wind shot takes a 5 iron. Same 200 yds uphill into the wind takes a 3 iron. 200 yds down hill with a tail wind 7 iron.
Gravity and air drag.

[longrange1]

Disagreement about bullet drop

Ozarkpugs

If that's true then why do most shooters shoot over the target(high)when shooting up or down hill?


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[ACfixer]

http://www.millettsights.com/downloads/shootinguphillanddownhill.pdf

ALWAYS aim lower for an uphill or downhill shot.

[dwalker]

It's good to know how to do it manually too in case your batteries die or the device overheats from being left in the sun on a hot day.
If you print this out and cutout the little chart, it's small enough to keep in your logbook and you will never be without it:
http://caprc.com/angle-of-fire.pdf

I have it it in my logbook along with some other handy stuff. And yeap, phones overheat when left in the sun on a 100deg day for sure.

[Brush Guard]

To put it simply. If you shoot at a horizontal target at say 400 yds and scored a bullseye, then shoot again at a target at 400 yds but at a 45 degree angle your shot will impact high compared to the horizontal level shot. Also it doesn't matter if the shot is up or down. It will still impact high compared to a level shot.

^^^^ This^^^^

The Rex has a good vid explaining Actual Horizontal Range vs. True Range.

https://www.youtube.com/watch?v=cKqZdHRlKfo&list=PLJUaiRIEduNXoal2_PkBZi0vDCIcEPxUn&index=33

[FUCA2AFTW]

Just imagine on a windless day shooting down from the top of a skyscraper at someone exactly below you entering it at ground level...no gravity effect, no compensation left, right, up, or down is needed. Bullet travels exactly parallel to direction of gravitational force (towards the center of the earth) so there is nothing to compensate for (obviously you probably haven't sighted your scope for this situation).

The other extreme is firing tangential to the circumference of the earth which is exactly perpendicular to gravitational force vectors and the amount of compensation required is at a maximum.

Every angle in-between these two extremes is an "in-between" case and you need "fancy" software, or just a calculator and the proper equations, or just a look-up table like that posted by AR15barrels.

[kcheung2]

I have a sneaking suspicion this topic came up because of the LV shooter...

[Scottie15]

This of this like a physics problem. Gravity is the vertical vector working to pull the bullet down. Let's just focus on the vertical component. Bullet drop is a function of the horizontal distance of travel. If you increase the angle of the shot (either up or down), the horizontal distance to the target decreases (is closer). The line of sight distance changes from the true horizontal distance as you add an angle component to the shot.

From the wiki article:


Gravity works on the bullet for the amount of time (distance) it takes the bullet to get to the target. The amount of time gravity works on the bullet decreases if you have an angled shot because the horizontal distance decreases. This means you will hit high because your line of sight distance is longer than the true horizontal distance (time) where gravity is pulling the bullet down.

[WMG]

This of this like a physics problem. Gravity is the vertical vector working to pull the bullet down. Let's just focus on the vertical component. Bullet drop is a function of the horizontal distance of travel. If you increase the angle of the shot (either up or down), the horizontal distance to the target decreases (is closer). The line of sight distance changes from the true horizontal distance as you add an angle component to the shot.

What the guy above me said...

[ozarkpugs@gmail.com]

Ozarkpugs

If that's true then why do most shooters shoot over the target(high)when shooting up or down hill?


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Because they shoot for the distance between the barrel and target gravity pulls on horizoal not down to the ground so if up hill angle is steep enough it could be 400 yards to Target but 300 yards to point under the target which is on same horizoal plane as the barrel

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