Question about zeroes and shooting height difference

[radiotom]

So imagine this scenario...

My AR-15 is zeroed at 200 yards from a bench. I placed the target I used when I zeroed at the same height as my barrel.

Now, how would my zero be impacted if I were 20 feet higher than my target, laser measured at the same range? Below is a link to a crude drawing explaining the difference.

http://i.imgur.com/z5qEPGb.png

Essentially I'm the same distance away...but would gravity play a factor?

 

[ngnrd]

The horizontal distance is the only measurement that matters.

But, for the distance and height give in your hypothetical, the difference in horizontal distance is only about 4 inches.

 

[Doc7]

In this case, with 200 yards as the hypotenuse of the triangle and 6.67 yards as one leg, the horizontal leg is 200.1 yards. So, there will be negligible difference in drop at this range vs a 200 yard shot.

Alternatively, hunting with a .22, a critter in a tree that is 20 yards distance and 60 feet high, would range out and visually appear to be 28 yards away. This is a much more significant case of trajectory impacts.

 

[torqem]

Normally, such questions are related to shooting on mountains, or maybe from tall buildings in the case of a sniper. people believe that they tend to shoot low when firing uphill, and the reverse (shoot high) when firing downhill. But as the man said, the only thing effecting the bullet in this regard is gravity, which is related to horizontal travel. You can laser range the target as being 400 yds away, but if the horizontal travel (up or down hill now) is just 200 yds, and you hold for 400 yds, you will shoot over your target, by a foot or so, depending upon the velocity and shape of the bullet.

 

[Notoast]

Gravity will cause you to shoot high in this case. The NSSF has a nice video that describes how to compute the angle range.
http://www.youtube.com/watch?v=wTSBcNgGMNo

 

[jmr40]

Not enough angle to worry about.

 

[Art Eatman]

Any angle flatter than around 30º won't make enough difference to notice, inside of 300 yards.

If you're zeroed at 200, you have about five or six inches of drop at 300. Cosine 30º = 0.866, so at 300 yards the bullets thinks it's travelled 267 yards. So you're off an inch or two at most.