If you're shooting at a steep uphill or downhill target at long distance and you don’t compensate for the difference in gravity, you’ll miss. Rifle expert Jeff Johnston shows how to make that shot! Posted on 09/22/2017 8:33:22 AM PDT by w1n1
If you're shooting at a steep uphill or downhill target at long distance and you don’t compensate for the difference in gravity, you’ll miss. Rifle expert Jeff Johnston shows how to make that shot!
Some hunters know that when facing a long downhill shot angle they are getting slightly lower than normal. That’s because gravity pull is greatest on objects that is parallel to earth. And so what this means is that a bullet fired at an angle won’t drop as much as one fired over level ground. But surprisingly this also means that a bullet will strike fire when shooting up hills as well.
Of course how much higher a bullet will hit is a product than the distinctness of the hill and the range to the target. For example 300 yards shot at a 45 degree angle which is pretty darn steep with this .306 right here with strike constantly six inches high. So generally hunters taking shots at... Read and see the rest of this video on long range - extreme angle shot here.
I stopped right there. This fellow has NOTHING reliable to tell me about the physics of up/down shooting.
It is not being a grammar Nazi to note that much of this article is literally unreadable. It is an example of something I have noted before, you cannot actually determine whether the author even knew what he was trying to say since what he wrote is meaningless.
It’s about time. There was a how-to article in a magazine in the 1970s on the same topic.
the author, and many, are making the math mistake of assuming that distance over which the gravity is applied is measured by line of sight, not in the horizontal. This is a practical way of measuring distance in the case of shooting up/down a slope, but you have to compensate for the difference in the line of sight distance to the horizontal distance (some simple trig). So yes, this is someone who is trying to impress you with what he knows but cant apply properly the physics he wants to so impress you with.
I gotta get me one of those sweet .306 rifles.
In the figure, the shooter is compensating (elevating) for the line of sight distance. If he were to elevate in all three shots only for the horizontal distance (like in the level shot), his shots would be much closer to on target. There might be some smaller effect errors due to other things, but I believe this is the biggest source of shot error in the described scenario.
Painful read.
What is the name of the app?
I carry a ballistic card for my home loads. I have one for each rifle/bullet pair.
I’ve not found wind to be much of an issue...4-5 inches over 500 yards is the worst correction I’ve seen.
Angle is BIG.
The really cool thing about anti gravity ammo is that, when you fire straight up, gravity has no effect and you can easily hit the moon. Or Saturn if your aim is good, you hold your breath, and slowly squeeze...
I have the advanced version of this. Think it is only $14.99 now but worth many times more than that. I have been using it for many years and have upgraded along the way.
It is the vector. The direction of gravity is partially in the same direction as the bullet’s velocity. So it counters air resistance a bit and the bullet goes faster than it would if you shot horizontal. Shooting ‘up’ is the opposite. It is about the vector at which the gravitational force is offset from the direction of flight when you are shooting horizontal. So it deflects more.
A bit on sand paper on a .308 and that baby slides right in...
When we hunt black powder we always add a measure of salt to the powder.
Range to the target ( straight line, regardless of angle whether up or down) then measure the angle from shooter to target, look up the cosine if the angle on your data card- you probably can skip all the details and do every 5 degrees- maybe to 50 0r 60 degrees if you think you’ll ever shoot that steeply then simply multiply the gun-target line range in yards by that decimal ( it will be less than 1 from zero to 90 degrees), and shoot for that number.
Example- if your range is 9oo, and your angle cosine is .9, your actual range to the target is 810 yards. Hold over or dial in 810 and shoot. f the GT range is 400, the cosine is .80, then the actual range is 320.
In effect, the real issue is horizontal range, not shooter to target line distance. All the rest is noise.
Range to the target ( straight line, regardless of angle whether up or down) then measure the angle from shooter to target, look up the cosine if the angle on your data card- you probably can skip all the details and do every 5 degrees- maybe to 50 0r 60 degrees if you think you’ll ever shoot that steeply then simply multiply the gun-target line range in yards by that decimal ( it will be less than 1 from zero to 90 degrees), and shoot for that number.
Example- if your range is 9oo, and your angle cosine is .9, your actual range to the target is 810 yards. Hold over or dial in 810 and shoot. f the GT range is 400, the cosine is .80, then the actual range is 320.
In effect, the real issue is horizontal range, not shooter to target line distance. All the rest is noise.
Air is air, bullets do not speed up if shot downhill... All air resists bullets and slows them down. The effect of gravity has so little do with it other than in a theoretical lab setting, which we don’t actually shoot so in ignore it.
No bullet ever travels parallel to the earth anyway, except for maybe a microsecond if you level the bore line, Bullets are always dropping on a curved trajectory once they leave the bbl:, up in a vertical component to account for range, down once past mid range. Geesh. Applied physics, not theoretical.
All long distance shooting is better for it.
There is a typo in the article, so what?
This explains how to compensate, which was not the issue.
The issue is what are the physics which account for the counter-intuitive result — point of impact is higher (and effectively equal for the same up/down angle).
Flight time doesn’t change. Distance to target doesn’t change. Drop doesn’t change (the effect of gravity is still the same).
Explaining this is where shooters come up with the amusing and the absurd.
When shooting on level ground, bullet describes an arc, gradual in the beginning, and steeper at the other end.
The measured amount of distance between line of sight and line of barrel is the bullet drop at that distance.
The bullet will always drop at the same rate, as a function of gravity.
Now,Imagine a laser attached to the scope and another alongside the barrel, the two dots are spaced vertically on the target, getting farther apart with distance.
The vertical line from the top dot (barrel) and bottom (line of sight) is the actual measured drop at that distance. This forms a long right triangle, with the 90 degree formed by the vertical small line and the line of sight.
Now, imagine a 45 degree shot, up or down, and also imagine the same triangle composed of the barrel line, line of sight, and the vertical measured bullet drop. However, even though the two longer lines, the barrel line and line of sight are still the same divergent angle regards to each other, the short third line, the vertical line, must stay vertical (the actual bullet drop at that distance)and by doing so, it's bottom will no longer touch the line of sight line because the angle between the barrel line and vertical line has changed, because the vertical line must stay vertical, as a measurement of bullet drop due to gravity, and is therefore shorter and does not meet the lower line of sight line at that distance.
If you grab a couple of long sticks and place them in a small divergent angle, and make a third small stick to just touch and close the open end, then move the first swo stickc up or down, keeping the same angle relationship between the two, while keeping the third stick still straight up and down, and it's top touching the top stick, it's bottom no longer reaches the bottom line.
Hope this helps.
:-)
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