Shooting Up or Down Hill - why aim low?

Sometimes if you take a problem to extremes it's easier to work out what's going on.
Imagine shooting vertically up. You wouldn't have to aim off no matter what the range 'cos gravity wouldn't be dragging the bullet off course. Same if you shot vertically down.
Hope that makes sense.
 
because shooting over a flat plain gives a slight arc trajectory,,,, uphill or downhill its a very slightly different trajectory to your flat one
 
Basically you will have zero'd your rifle shooting in a horizontal plain. You know your bullet drops from the moment it leaves the barrel due to gravity pulling it down, so will gradually fall to the ground. Now if you aimed higher your bullet would travel further as you will have used the bullets energy to counter gravity and your bullet will go further. So if shooting down hill your are in effect using gravity, or fighting it to a lesser extent so "drop from horizontal zero" will be less and therefore you need to aim lower than if shooting at a horizontal target. Same applies for shooting up hill as again gravity will take a slower effect on something travelling above horizontal (until energy is lost, then it will drop like a stone).

Best thing is sit on a hill and shoot something at the bottom see what your "drop" is.
Good question though. Hope that was simple enough?
 
Sometimes if you take a problem to extremes it's easier to work out what's going on.
Imagine shooting vertically up. You wouldn't have to aim off no matter what the range 'cos gravity wouldn't be dragging the bullet off course. Same if you shot vertically down.
Hope that makes sense.

It does up to a point, but if you measure gravity accurately, it doesn't always pull straight down - ask the folk who launch ICBMs. It varies as well.

gravity map of the uk - Google Search

Regards

JCS
 
because shooting over a flat plain gives a slight arc trajectory,,,, uphill or downhill its a very slightly different trajectory to your flat one
Absolute rubbish. The bullet is always dropping from the time it leaves the muzzle. At no time does it rise in an arc.
The arc you see on the ballistic charts is because of the point of aim being higher.
 
Have a watch of this, there are others that offer an insight to what has already been mentioned regarding bullet path & bullet trajectory, distance to target and line of sight distance being fractionally different.

 
It is the horizontal distance that needs to be accounted for either above or below line of sight. Perpendicular to the gravitational pull...?

So if the target may be 500 metres away from the end of the barrel, because it is 300 metres up the drop will be the same relative to the sight reticule / elevation clicks, as if it was 400 metres horizontally...(3,4,5) sided triangle for ease of explanation.

Alan
 
In really simple terms, because that's what I understand, you only consider the horizontal distance. So it might be 200 yards away, but if you are shooting down at 30 degrees that will only be about 170 yards of horizontal distance so that's what you allow for.

With calibres that shoot +\- 1" to 200 yds or thereabouts at normal stalking distances it's not really something you need to worry about too much. Stretch out to 300 yds and start shooting at 30 degree angles (pretty extreme) and you need to factor it in.
 
In really simple terms, because that's what I understand, you only consider the horizontal distance. So it might be 200 yards away, but if you are shooting down at 30 degrees that will only be about 170 yards of horizontal distance so that's what you allow for.

With calibres that shoot +\- 1" to 200 yds or thereabouts at normal stalking distances it's not really something you need to worry about too much. Stretch out to 300 yds and start shooting at 30 degree angles (pretty extreme) and you need to factor it in.

spot on
 
Absolute rubbish. The bullet is always dropping from the time it leaves the muzzle. At no time does it rise in an arc.
The arc you see on the ballistic charts is because of the point of aim being higher.

I don't think this is correct. Each zero range has a secondary zero range as well when the bullet is travelling upwards, after that point, it reaches the top of the arc and starts falling down, intersecting the line-of-sight through the scope at the zero range. When you fire on the flat, you're actually shooting slightly angled up. A laser boresight would not necessarily join up with a laser shone accurately through the scope
 
Absolute rubbish. The bullet is always dropping from the time it leaves the muzzle. At no time does it rise in an arc.
The arc you see on the ballistic charts is because of the point of aim being higher.

So what happens is you was to fire vrtically upwards
 
If you fire a rifle parallel to the ground the bullet is always falling it is basic physics. Anyone who thinks different should spend more time shooting and less time on Google.
Even as in the stupid question about shooting directly up the bullet will always be falling - will it be falling left or right? Depends on your location due to the gravitational pull of the earth.
 
Absolute rubbish. The bullet is always dropping from the time it leaves the muzzle. At no time does it rise in an arc.
The arc you see on the ballistic charts is because of the point of aim being higher.
,,,,Where did i say it rises in an arc ,,,,,,,i meant what you said its the same thing its allways falling, ,he asked for a simple answer
 
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If you fire a rifle parallel to the ground the bullet is always falling it is basic physics. Anyone who thinks different should spend more time shooting and less time on Google

That's the point, though, if you are shooting horizontally, you're not firing the bullet parallel to the ground.

A bullet fired vertically upwards is not always falling. It is decelerating due to gravity and air resistance and the likelihood is that it will veer off course but it won't actually fall until it reaches it's apogee
 
Reminds me of the other pub quiz question, hold bullet in one hand and drop it at the same time as firing a rifle horizontally with the same type of bullet, which bullet hits the ground first
 
Reminds me of the other pub quiz question, hold bullet in one hand and drop it at the same time as firing a rifle horizontally with the same type of bullet, which bullet hits the ground first

They tested this on Mythbusters - they hit the ground at the same time
 
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