Question about field adjustment to D.O.P.E.

[Khsiebert]

This forum is clearly the haunt of some very bright minded individuals and capable marksmen, from whom I am seeking guidance. My question pertains to the method necessary to make elevation adjustments to compensate for an elevated shooting position relative to the target down range.

It is my understanding that ballistics programs assume a target altitude level with the shooting position ... and even my hard dope is based on similar conditions. However, if I am faced with a shooting environment where my target is 1000 yards downrange, but I am in a shooting position 75 feet higher than my target (in an elevated shooting position), how would I compensate for that field condition? Is there a standard cosine equation?

Thanks for your input.

[264Charlie]

The easy way is to use a iPhone ballistic program and enter the angle to the target. The programs are slick all you have to do is point you iPhone at the target.

How do you know the target is 1000 yards away? If you used a range finder or plan to you could get a range finder that adjust the range for the the angle. Bushy's, Vectronix and Leupolds do this


Lastly you can use a Slop Doper or similar product. Good write up at http://www.snipercountry.com/InReviews/SlopeDoper.asp" onclick="window.open(this.href);return false;

[AR15barrels]

Ballistics programs should all have an angle-of fire data entry to adjust for it.
If you were working only from a printed range card, you would adjust your dope by the factors on the following sheet:

http://www.caprc.com/angle-of-fire.pdf" onclick="window.open(this.href);return false;

[Khsiebert]

The cosine table is what I had in mind.

Does the cosine take into consideration the time of flight differential?, if you know.

Thanks.

[AR15barrels]

Does the cosine take into consideration the time of flight differential?

The cosine simply helps you shorten your "effective range to target" to correct your dope.
Your corrected dope takes into account the shortened flight time.

[buffybuster]

75ft higher elevation over a Line of Sight distance of 1000yds (3000ft) effect on bullet trajectory is so inconsequential that it is entirely negligible.

[robert hode]

General rule of thumb: If the angle of your shot is up OR down, in BOTH instances, aim LOWER than normal.
How much depends on how far and at how steep of an angle you are shooting.
For practical purposes, unless you're shooting from the roof of a multi story building to the street below or visa versa, it aint worth the effort to worry about.

DISCLAIMER: I'm not saying these are the scenarios in which we shoot. It just seemed like good visual.

[GforceJunkie]

My trig is pretty rusty, but 75 foot rise over 3000 feet is less than 2 degrees. Small enough to ignore it.