Everything you wanted to know about inclined fire shooting:

http://www.exteriorballistics.com/eb.../article1.html
Blaine, I believe the formula should read:

BP = D*cos(a) - SH*{(R - Rz)/Rz} - Dz*R/Rz

Where:

(a) = bore angle to the horizontal

BP = bullet path

D = drop, horizontal range

SH = sight height

R = range

Rz = zero range

Dz = drop at zero range, horizontal

From this formula we can see that the BP correction at any range is: D*(1 - cos (a))

This correction is always substracted to your bullet path.

Maybe a more practical solution to this problem is to use the scope angle of elevation above the horizontal. For example a 175 SMK @ 2680 fps, std. cond., needs to compensate for: 2.5" (drop) + 1.7" (sight height) = 4.2" to zero at 100 yds. This is, 4.0 MOA of elevation are already dialed into the scope when you are zeroed at 100. If your come ups from this 100 yds zero to 1000 yds is 36.6 MOA, you really have 40.6 of elevation into the scope. Think in terms of "scope elevation" instead of drop or comeups!

To correct for any angle at any range multiply "scope elevation"*cos angle

This elegant solution was suggested by BMG Mike back when we had some discussions at SH. It is faster than the solution explained in the Sierra site and produces results with similar accuracy.

For any angle <30º, if your base zero is 100 yds you can just use: come ups * cos angle and you'll be veeery close.

Remember all these methods are a simplification of the problem, because they disregard the small variations of bullet drop due to the air pressure and gravity effects on angled shots (which are taken into account in some programs like the Infinity), but these effects are minor and of opposite signs and almost cancel each other out.