Shooting down at a target

[.308 Norma]

Maybe I am getting senile, but I thought that is what I said.

So did I.

 

[ATLDave]

This gets more intuitive if you ask how much drop a shot straight up or straight down will have. The answer, of course, is zero. There will be velocity loss or gain, respectively, but there will be no deviation-from-straight-drop (at least until the upward one runs out of velocity and comes back down!).

 

[Scooter22]

The Vegas shooting got me to wondering about the geometry of a shot like that. Shooter was about 400 yards away and 100 yards or so high. If your gun is zeroed for shooting on level ground, what does the height elevation of the shooter do to the point of impact?

Hunters in mountains would have to deal with this if they are on a mountain and game is below them.

From his position shooting down into a crowd of more than 20K I don't think there was much geometry or aiming. Just dumping mags of ammo in that direction. If he had some tracers mixed in thats all the aiming needed.

 

[coloradokevin]

Some of the advice I'm seeing here is a bit peculiar.

If you're doing Kentucky windage the old rule is that you'll want to aim lower for both uphill and downhill shots. What you need to remember here is that your bullet is impacted by gravity only for its horizontal distance to the target (the portion parallel to the surface of the earth). The slant distance that you're measuring is actually the long edge of the triangle (the hypotenuse). You need to mathematically figure out the distance of the horizontal component of your shot, which is what you'll be aiming for.

If you have a calculator and a couple of basic tools this isn't hard to work out. Here's how it goes: Let's assume that you have a rangefinder and an inclinometer for this shot, because those tools would be close to essential to work out the math easily.

You range your target, and find that it is 450 yards away. You check your inclinometer and find that your target is at a 23 degree down angle from you.

Take the COSINE (COS button) of your 23 degree angle, and you'll get 0.920. Multiply 0.920 X 400 yards, and you'll get 368. Now aim as if you're shooting at a target that is 368 yards away. You'll find that the effect is more pronounced as your angle increases.


As for the A-hole in Vegas, I've already heard members of the media refer to this guy as an expert marksman with sniper-like skill. That's total BS. The guy fired thousands of rounds into a tightly packed crowd of people. He used the fish in the barrel approach, and nothing I said above applies to anything that this psychopath did that night.

 

[340PD]

I try not to over think this. When shooting my gun or bow. If I am shooting uphill or downhill (treestand height) I aim a bit lower than normal and the results have always been perfect.

 

[roval]

Some of the advice I'm seeing here is a bit peculiar.

If you're doing Kentucky windage the old rule is that you'll want to aim lower for both uphill and downhill shots. What you need to remember here is that your bullet is impacted by gravity only for its horizontal distance to the target (the portion parallel to the surface of the earth). The slant distance that you're measuring is actually the long edge of the triangle (the hypotenuse). You need to mathematically figure out the distance of the horizontal component of your shot, which is what you'll be aiming for.

If you have a calculator and a couple of basic tools this isn't hard to work out. Here's how it goes: Let's assume that you have a rangefinder and an inclinometer for this shot, because those tools would be close to essential to work out the math easily.

You range your target, and find that it is 450 yards away. You check your inclinometer and find that your target is at a 23 degree down angle from you.

Take the COSINE (COS button) of your 23 degree angle, and you'll get 0.920. Multiply 0.920 X 400 yards, and you'll get 368. Now aim as if you're shooting at a target that is 368 yards away. You'll find that the effect is more pronounced as your angle increases.


As for the A-hole in Vegas, I've already heard members of the media refer to this guy as an expert marksman with sniper-like skill. That's total BS. The guy fired thousands of rounds into a tightly packed crowd of people. He used the fish in the barrel approach, and nothing I said above applies to anything that this psychopath did that night.

that's what i have been saying but just to correct in your example above 0.920 X 450 yrds.....one thing that's useful for known positions is to use google earth there's a ruler feature and it gives you the range between 2 points. its actually accurate. i tried it on the satellite view of our city range and was within a yard or 2 of the stated range of the targets . the 225 yrds and 565 yrd target were close enough. i learned about this from a hunting video.

 

[Jenrick]

Yep a map study or range card, is an excellent way to know the horizontal distance.

-Jenrick

 

[coloradokevin]

I try not to over think this. When shooting my gun or bow. If I am shooting uphill or downhill (treestand height) I aim a bit lower than normal and the results have always been perfect.

How much you overthink this depends on how critical your shot might be. A couple of inches on a game animal at tree stand heights rarely matters, but a couple of inches of offset at a hostage taker holding a hostage in a building can be a bit more substantial.

The math based method I mentioned above has been simplified greatly in recent years with ACI on rifles (Angle Cosine Indicators). They basically just give you the answer to most of the equation I mentioned above, and that answer is then multiplied by your slant distance to get your shooting solution. Again, doesn't matter to 98% of shooters out there, but it sure matters a lot in a few select situations.

 

[ms6852]

Everyone should look at this, takes less than 20 minutes but there is a lot of great information for the novice shooter who wants to learn long range shooting at angles.

 

[GarySTL]

OK, using my ballistics app, Strelok Pro and my 6.5 CM data with a 200 yard zero, here are the numbers.
Range 400 yards
Slope angle 0
Drop is 18.9"

Slope angle 25 degrees
Drop is 15.1"

Slope angle 45 degrees
Drop is 7.1"

Slope angle 60 degrees
Drop is -1.3" Strike is higher

Get your calculators out and do the math.

 

[Flechette]

Aim low.

Think of it this way: a zeroed in rifle has the line of sight and the bullet trajectory matched at a certain distance. The trajectory is affected by gravity.

If you shoot straight up, or straight down, the bullet will cross the line of sight sooner (closer to the rifle) and keep right on going away from the line of sight.

Shooting at an angle also experiences this effect, but it depends on how much of an angle.

But no matter what, you need to aim lower than for a horizontal shot.