I'm wondering about effects of shooting up & down hill

[Ray B]

I'm aware of the effects of gravity on bullet drop from line of sight- ie the total horizontal distance compared to the total distance and subsequent changes in sight. What I'm wondering is if a bullet is fired from a high position over a long distance, will gravity cause a change in the bullets velocity? For example, say I am shooting at a target that is 800 horizontal yards away and the vertical drop between firing point and target is 600 yards. The distance the bullet travels will be 1000 yards. (3-4-5 right triangle). If the bullet is fired at 3000 fps and the velocity was constant, it would cove the distance to the target in 1 second. the bullet drop with be 16' however due to the angle of view for the shooter, the apparent drop will be less. I haven't figured out the sine function for that- What I'm wondering is that the direction of the pull of gravity is partially in line with the direction of bullet travel, would that portion of gravity cause a relative increase in bullet velocity? If it did, the bullet would still be slowing due to air resistance, but the rate of velocity decrease would be less than if the bullet were fired horizontally. And since it seems that this reduced decrease in loss of velocity would factor in on a 1000 yard shard, just how much would it change the point of impact from the calculated point of aim?

 

[Forrest Halley]

The bullet is affected by gravity over the linear distance. You haven't given a BC so who knows. Also need temp and altitude and pressure to start.

 

[Hogpatrol]

Uphill or downhill, gravity is the same and the distance shot is the base leg of a right triangle, not the hypotenuse. In other words, gravity is not perpendicular to the hypotenuse.
Taking out atmospherics, picture a plumb bob dropped from your uphill target. The straight line distance is 1000 yards to the target but the distance from the plumb bob at your elevation to where you are standing is 100 yards. Bullet drop will be the same as if you were shooting 100 yards straight at zero degrees.

 

[YancyW]

Aim low for both....

 

[Ray B]

I guess I'm not being clear. The question in simple terms is: does a bullet fired toward the Earth decelerate at the same rate as one fired away from the Earth. A yes or no answer doesn't need all the additional qualifications being requested.

 

[Hogpatrol]

I guess I'm not being clear. The question in simple terms is: does a bullet fired toward the Earth decelerate at the same rate as one fired away from the Earth. A yes or no answer doesn't need all the additional qualifications being requested.

Yes

 

[K E Johnson]

I learned the hard way on this one. Hogpatol nailed it.

 

[Hogpatrol]

Rangefinder with an inclinometer and use your dope chart. Shoot, retrieve.

 

[tedthorn]

Aim low for both....

No

 

[Ray B]

So if you're in a helicopter hovering at 5000 feet and you have two rifles, same cartridge and bullet. One you fire straight at the ground and the other you fire at a target 5000 feet away. Allowing for the slightly thinner air at 5000 feet and the trajectory due to gravity, Fired at the same time, which bullet would get to the target first?

 

[Hogpatrol]

Same time for both if no bullet drop. Yours is an apples and oranges comparison.
Edit: In a vacuum, a bullet dropped from the end of the barrel centerline and one fired in the gun will hit the ground at the same time.

 

[IdaRam]

A few questions; (intended more to provoke thought than an answer)
If you fire an arrow from a bow at a target 100 yards away on an up-slope of 30 degrees, and then fire an arrow at a target 100 yards away on a down-slope of 30 degrees, will both arrows be traveling at the same velocity when they reach the target? And will the same hold over be required for both targets?
Similar scenario, different projectile. If you are standing on a 30 degree slope and throw a softball up hill then throw another softball down hill at the same speed, are the two velocity curves over distance the same? Trajectories? Carry distance?
What if the softball is thrown straight up vs straight down? Gravity certainly has an effect on velocity here right?

I suspect gravity may have the potential to effect velocity of the rifle bullet when fired up vs down hill, but the effect may be so minute as being difficult or impossible to measure. Atmospheric drag has orders of magnitude greater effect than the effect of gravity on the projectile velocity.
Kinda like spin-drift or Coriolis effect VS wind drift in a 40 mph wind at 500 yards. Wind will be a major factor. Affect of spin drift and Coriolis effect are virtually zero, but the influencing factors are still environmentally present, just no measurable effect.
I think...

 

[sestoppelman]

No

Wrong
https://www.chuckhawks.com/shooting_uphill.htm

 

[Hogpatrol]

A few questions; (intended more to provoke thought than an answer)
If you fire an arrow from a bow at a target 100 yards away on an up-slope of 30 degrees, and then fire an arrow at a target 100 yards away on a down-slope of 30 degrees, will both arrows be traveling at the same velocity when they reach the target? And will the same hold over be required for both targets?
Similar scenario, different projectile. If you are standing on a 30 degree slope and throw a softball up hill then throw another softball down hill at the same speed, are the two velocity curves over distance the same? Trajectories? Carry distance?
What if the softball is thrown straight up vs straight down? Gravity certainly has an effect on velocity here right?

I suspect gravity may have the potential to effect velocity of the rifle bullet when fired up vs down hill, but the effect may be so minute as being difficult or impossible to measure. Atmospheric drag has orders of magnitude greater effect than the effect of gravity on the projectile velocity.
Kinda like spin-drift or Coriolis effect VS wind drift in a 40 mph wind at 500 yards. Wind will be a major factor. Affect of spin drift and Coriolis effect are virtually zero, but the influencing factors are still environmentally present, just no measurable effect.
I think...

Yes to the arrow question. Your arrow (or bullet) is dropping as soon as it stops being pushed by whatever propels it. For a bullet, soon after it leaves the bore, The arrow as soon as the nock leaves the string.

 

[tedthorn]

Wrong
https://www.chuckhawks.com/shooting_uphill.htm

Range the target with a rangfinder that has angle compensation then hold dead on for said yardage or dial for that range and kill the animal.

The article you site is a bit antiquated

 

[Cam Moon]

I agree 100% with the fact that gravity has it's affect on a projectiles trajectory based on the HORIZONTAL DISTANCE the projectile is traveling, rather than the perceived (or actual) distance traveled. Example: You're bow shooting a cat from a tree. You're only 5 yards from the bottom of the tree and the cat is 35 yards up the tree. You have to shoot as if it's 5 yards away. If you use your 35 or 40 yard pin, you're gonna shoot clear over it.
HOWEVER I interpreted the OP's question differently. I thought @Ray B was asking more about the SPEED of the projectile. So if I'm firing something down, vs up, vs horizontal, what affect does gravity have on the speed? My mind tells me that if I'm firing down at something vs up at something, that after X many yards, my downwards projectile would be going faster than my upwards projectile. Enough to make a difference?
But then again, I could have totally misread the question! LOL

 

[sestoppelman]

Range the target with a rangfinder that has angle compensation then hold dead on for said yardage or dial for that range and kill the animal.

The article you site is a bit antiquated

Not talking about using a rangefinder or the latest and greatest fad gizmo! Old article or not the facts remain the same. Hold low for extreme uphill or downhill. Nothing new, except for the rangefinder crowd that never heard of this basic rule.

 

[IdaRam]

Yes to the arrow question. Your arrow (or bullet) is dropping as soon as it stops being pushed by whatever propels it. For a bullet, soon after it leaves the bore, The arrow as soon as the nock leaves the string.

Yes, I believe we agree on that. But not really what we are talking about

 

[tedthorn]

Not talking about using a rangefinder or the latest and greatest fad gizmo! Old article or not the facts remain the same. Hold low for extreme uphill or downhill. Nothing new, except for the rangefinder crowd that never heard of this basic rule.

Ok....how about a different angle of thought
250 zero
Anything under 300 you kill the animal
Up or down only changes the hunters perspective of how far.....it doesn't change physics

 

[Shootist43]

What Yancy W said i.e. "hold low in both cases" is TRUE in one aspect. You will be holding lower than what you'd expect to be, based on the apparent distance. As stated the distance of bullet travel is the bottom leg of a right triangle not the "apparent" distance which is the hypotenuse. Hogpatrol's post is spot on.