I have used this calculator for a while now.. Feel free to download it and please let me know if you find any bugs. Includes following 6-dof corrections to vertical and horizontal deflections:
Spin drift (Litz)
Vertical and horizontal Coriolis (Litz)
Up/downhill shooting (Litz's improved riflemans rule)
Range wind drift (McCoy)
Aerodynamic jump aka crosswind vertical drift (Litz)
Wind weighting factors (McCoy)
Muzzle velocity temperature coefficient (linear inter/extrapolation)
Effect of atmospheric conditions to vertical zero range
Possibility to use horizontal zero to compensate spin drift for short ranges
I would say this is as accurate as it gets. Recommended for extra long ranges. I think there is no more external ballistic phenomena to correct. Or maybe effect of vertical wind component could be included? Calculator is pretty easy to use at the range when there is own sheet for every gun/load. Before shooting just "TARGET INFORMATION" and "ATMOSPHERIC CONDITIONS" values have to be changed. Everything else have to be set only for once. There is two default sheets: one for BC input and another for lapua bullets (radar drag data available).
You can download it from link below:
http://www.2shared.com/file/YEE1WaWl/Ballistic_calculator.html