Range and inclination

[pewpewfever]

I’m still too noob to even know what keywords to search for this information, so please forgive the stupid question. I can see my ballistics calculator has an ability to adjust for angle of inclination. I tried measuring that angle and using it with little success. Also, it seems the given ranges at matches might not be line of sight range, but anither range that is the base if the triangle or something like that? So you don’t need to input the angle of inclination? I’m confused. Can someone please explain? Also, I ordered a rangefinder that is a sig 2200mr and I think it can report the range in two different ways, with one being line of sight, and the other being the base of the triangle so you can ignore the angle. Is that correct? Finally, if I ever reticle range, then do I need to measure the angle with something like a suunto clinometer and either input the angle or do the math to find the base of the triangle? Thanks.

 

[pewpewfever]

Found some good info I think. Useful keywords are slant range distance and rifleman’s rule.

 

[Erno86]

Nightforce sells a Nightforce Angle Degree Indicator A122 with a picatinny rail mount --- And Brownells sells a cosine indicator with a scope ring.

You can also roughly tell the vertical angle with arm extended out level with the horizon and go up or down with the extended arm in graduations of a degree, which is 0 cosine of the angle or 90 degree sine angle and straight-up vertical being 90 degree cosine or 0 degrees sine and vice versa for below horizon shots.

Do you need the formula for the actual cosine or sine reduced actual distance?

Some guys can figure out the calculations in their heads...I use a pocket calculator.

For some examples:

For below horizon shots...

900 feet (slope distance) times the sine of the vertical angle 125 degrees 45 minutes 27 seconds (convert the sine of the angle to decimals of a degree) = 730.35 feet - actual horizontal distance

900 feet (slope distance) times the cosine of the vertical angle 35 degrees 45 minutes 27 seconds (convert the cosine of the angle to decimals of a degree) = 730.35 feet - horizontal distance