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

Standard Velocity

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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

Not true. Uphill and downhill shooting are not about correcting for any sort of optical illusion. The physics of the bullet dropping has a changing variable with angle relative to plumb.

Think of gravity as a constantly blowing wind going straight down. All of our calculations assume this factor at 90 degrees in trajectory charts. When you start shooting more “into the wind”, or uphill, gravity will have less impact on how far it pushes the projectile off it’s original axis. Shooting squirrels high in a tree with a 22 will illustrate this on a smaller scale.
 

Hogpatrol

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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?

More mud in the water. :D

An object dropped from rest will increase its speed until it reaches terminal velocity; an object forced to move faster than its terminal velocity will, upon release, slow down to this constant velocity.

Terminal velocity is achieved, therefore, when the speed of a moving object is no longer increasing or decreasing; the object’s acceleration (or deceleration) is zero. The force of air resistance is approximately proportional to the speed of the falling object, so that air resistance increases for an object that is accelerating, having been dropped from rest until terminal velocity is reached. At terminal velocity, air resistance equals in magnitude the weight of the falling object. Because the two are oppositely directed forces, the total force on the object is zero, and the speed of the object has become constant.
 

tedthorn

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Not true. Uphill and downhill shooting are not about correcting for any sort of optical illusion. The physics of the bullet dropping has a changing variable with angle relative to plumb.

Think of gravity as a constantly blowing wind going straight down. All of our calculations assume this factor at 90 degrees in trajectory charts. When you start shooting more “into the wind”, or uphill, gravity will have less impact on how far it pushes the projectile off it’s original axis. Shooting squirrels high in a tree with a 22 will illustrate this on a smaller scale.

Regardless....you are shooting on the horizontal not the hypotenuse.
I must be lucky..... Ive killed a lot of stuff in the mountains
 

Vinootz

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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?
Aim lower for both. Learn how cosine(adjacent hypotenuse) apply to shoot angles. Also, there are field hunting tools for convenience
 

Ray B

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I'm familiar with the effects of gravity on the trajectory of a bullet. what I was wondering was what effect gravity had on bullet velocity.
 

fourfive8

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I would think air resistance/friction would have by far the greater influence. I think I understand the question and at any reasonable range, the influence of gravity on the velocity, either a slight "pull" if on incline from horizontal or slight "push" if on decline from horizontal would be minimal.

In very simplistic graphic terms.

The maximum gravitational influence would be 90* angle, either straight up for -32ft/sec/sec or straight down for +32 ft/sec/sec.

A 45* angle, up or down would be approx. -16 ft/sec/sec. or +16 ft/sec/sec respectively... approximate because of parabolic curve of trajectory.

Horizontal would be approx. net zero influence... approximate because of the parabolic curve of trajectory.

I don't know for certain but that is my guess- it's late and my brain is tired of viruses and riots
 

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Screen Shot 2020-06-08 at 22.10.27.png
 

Vinootz

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Gravity is a constant. The less velocity the more it’s effect. But I figure you know that. I’m not sure this forum is the best source for physics formulas if that’s what you are looking for. Although on the other hand, I’d wager there are a few folks here that probably could. Still just use adjacent divided hypotenuse. Better yet get an inclinometer or mil dot master type of card.
 

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My opinion...get close and don’t worry. Everyone wants to be a sniper these days. How about being a hunter? :whistle:
 

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My opinion...get close and don’t worry. Everyone wants to be a sniper these days. How about being a hunter? :whistle:

Yeah, but shooting something close is too easy.:p:D
 

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Last time in RSA, I couldn't get any closer to a springbok than 300 yards. In the Karoo, those guys can see you from a long way. They're don't have a lot of confidence when seeing something moving. Must be those other guys that want to eat them.
 

Ray B

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As I run the numbers on shooting up vs down, the main conclusion that I come-up with is that excepting for trajectory, gravity has little effect on the bullet. Accelerating or decelerating at 32 ft per second is a small fraction of the bullets velocity from a modern cartridge (2000+ fps) with a time of flight of one second or less. There will generally be more variation shot to shot in most loads than the change due to gravity.
 

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As I run the numbers on shooting up vs down, the main conclusion that I come-up with is that excepting for trajectory, gravity has little effect on the bullet. Accelerating or decelerating at 32 ft per second is a small fraction of the bullets velocity from a modern cartridge (2000+ fps) with a time of flight of one second or less. There will generally be more variation shot to shot in most loads than the change due to gravity.

Exactly! The affect of gravity on velocity at different angles from horizontal is very small compared to the measurable difference between POI and POA at those angles. Two different things.

Visualize a right triangle. The base of the triangle is horizontal to Earth's surface. That is the horizontal range component that determines the shape of a bullet's trajectory relative the the shooter's sight line. For practical purposes, the amount of compensation for most hunting conditions (angles) and ranges is fairly small. In all cases no matter, if the angle is up or down from horizontal, the correction for POA is always slightly lower to maintain same POI.

It may come into play if one forgets that principle or the ballistics involved on a fairly long shot for example at a steep uphill angle and thinks (erroneously) that it will require a slight hold over to compensate (because the bullet is "fighting" gravity going uphill). I think that is the most common mistake I hear hunters make and can result in a miss high.

Horizontal component  .png
 

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Exactly! The affect of gravity on velocity at different angles from horizontal is very small compared to the measurable difference between POI and POA at those angles. Two different things.

Visualize a right triangle. The base of the triangle is horizontal to Earth's surface. That is the horizontal range component that determines the shape of a bullet's trajectory relative the the shooter's sight line. For practical purposes, the amount of compensation for most hunting conditions (angles) and ranges is fairly small. In all cases no matter, if the angle is up or down from horizontal, the correction for POA is always slightly lower to maintain same POI.

It may come into play if one forgets that principle or the ballistics involved on a fairly long shot for example at a steep uphill angle and thinks (erroneously) that it will require a slight hold over to compensate (because the bullet is "fighting" gravity going uphill). I think that is the most common mistake I hear hunters make and can result in a miss high.

View attachment 352668

To simplify, are you saying that if one was "dialing in" a range on a turret scope to their target, the appropriate distance to dial-in would be 433 yards and 250 yards, respectively?
 

RayAtkinson

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Intresting thread, but in the real world, you aim low on the leg for a shoulder shot, you then have a good deal of error correction, nothing changes up or down, normally you don't have time to analize the situation....I fly by the seat of my pants in most hunting situation and so far its worked pretty darn good. I know the trajectory of my gun at point blank to 400 yards, and perhaps 500 but out there many things can happen, I have a personal opinion on the subject, don't shoot past 300 yards except under unusual situation...

I also sight in my guns at 3"s high at 100 yards, 4 inches high at 200, on at 250 to 275 depending on caliber and load, center mass at 300 and top line at 400 on big animals..I also do this testing at home, dont' take it for granite, know the guns trajectory at 100, 200, 300 and 400, it can vary...and I have tested my trajectory shooting steep downhill and steep uphill, and played around with that...This testing avoids guess and by gosh that's in print and claimed to be actual, when in fact is just a ball park figure..do your homework to be a better game shot..When I see an animal I don't prank around with gimmicsd like rangefinding etc, etc. I quickly find a natural rest if available, or shoot offhand if I must, its paid off in aces over the years, Not applicable advise for those that hunt from stands, and have all the time in the world for an ambush..nor for long range shooters (not hunters IMO)..but to each his own and that's another thread.
 

fourfive8

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And yes :) Personally, I'd never shoot that far but basically the horizontal distance to target is what counts as far as trajectory goes. In the example graphic, that bullet is still having to pass through 500 yds of air, possibly swirling turbulent air, under field conditions and from questionable rest, held by a human and fired by a human pulling the trigger and with a rifle/ammo that has a built-in POI accuracy dispersion of X. :)
 

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Absolutly….
 

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Intresting thread, but in the real world, you aim low on the leg for a shoulder shot, you then have a good deal of error correction, nothing changes up or down, normally you don't have time to analize the situation....I fly by the seat of my pants in most hunting situation and so far its worked pretty darn good. I know the trajectory of my gun at point blank to 400 yards, and perhaps 500 but out there many things can happen, I have a personal opinion on the subject, don't shoot past 300 yards except under unusual situation...

I also sight in my guns at 3"s high at 100 yards, 4 inches high at 200, on at 250 to 275 depending on caliber and load, center mass at 300 and top line at 400 on big animals..I also do this testing at home, dont' take it for granite, know the guns trajectory at 100, 200, 300 and 400, it can vary...and I have tested my trajectory shooting steep downhill and steep uphill, and played around with that...This testing avoids guess and by gosh that's in print and claimed to be actual, when in fact is just a ball park figure..do your homework to be a better game shot..When I see an animal I don't prank around with gimmicsd like rangefinding etc, etc. I quickly find a natural rest if available, or shoot offhand if I must, its paid off in aces over the years, Not applicable advise for those that hunt from stands, and have all the time in the world for an ambush..nor for long range shooters (not hunters IMO)..but to each his own and that's another thread.

3" high at 100.......4" high at 200....on at 250-275.....dead on at 300.....top line at 400.....steep uphill and steep downhill...ball park figure....don't prank around with gimmicks like rangefinders etc. etc....quickly find a natural rest.....or shoot offhand......

Fu...I can't shoot for shit........luckily I am only 50.....
 

Vinootz

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Yeah, but shooting something close is too easy.:p:D
Is it? Developing skills to best the quarry’s senses and get close l requires a lot more ability than sniping from long distances. Your comment twists reality. Are you a millennial? Lol
 

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