John/MilDot1960: Sorry, I probably didn't write it out as clearly as I'd hoped - what I meant is that for my .308 with a tight right twist barrel I start to consider/include SD in calculations starting at around 400m, below 400meters I'll use the same amount of windage dope whether the wind is blowing right-to-left, or left-to-right (azimuth 90 or 270). Using my range card when over 400 meters I'll slowly start adding extra dope for SD (1 click at 400m, and about 3 clicks at 1km - which corresponds to your calculations) for right-to-left wind, or subtract for left-to-right wind. Finally, at 1km I add one right click for horizontal coriolis (in USA and in Europe - around 43-46th degrees latitude - imagine it as correcting for an 'extremely mild wind' blowing from your 9 o Clock). For vertical coriolis you add an elevation click if you're shooting in western direction, for eastern direction you subtract an elevation click, and if you're shooting north or south you just ignore it.
Example, at 725 meters for 3ms wind coming at 3 o Clock I'd use 8 clicks dope, but for the same strength 3ms wind coming at 9 o Clock I'd use 12 clicks dope (numbers just for illustration, don't have my range card on me
Of course this is a bit simplified, in the regions I shoot the wind pretty much never stays constant (intensity and/or direction), so I just estimate overall wind effect on bullet combining what I see at three or four different positions (I usually consider the wind at the shooting position, then in the first third of bullet's path, at the bullet's highest trajectory point, and finally what I see happening at the target as having the least influence), so in my example above I estimate the combined wind effect to be about 10 clicks for this 725m target, I dial it in and then for left-to-right wind I subtract two clicks for SD totalling 8 clicks dope, or add the 2clicks for right-to-left wind for a total of 12 clicks dope. I don't worry about coriolis until well over 900meters.
Note - Kestrel with Horus (not sure about the new one with Applied Ballistics software though) does this automatically for you - if you manually change the direction/azimuth of the wind (say 90 to 270), you will get different windage value, and you also get slight variances if you change the geographical latitude value in the settings, or modify the twist-rate in 'Gun' settings. If you are using other ballistic software which does not let you change the latitude, modify the twist rate, or if you get same windage value calculation at all distances whether the wind blows from your right or left, you may need to do the SD/CE calculations/adjustments on top of the software's ballistic solution.
Of course then you also have the other factors – visual mirage image shifting, position of the sun and clouds in relation to the target, etc. that no ballistic software that I know of takes into account, and for those you just have to rely on your gut/experience.
Hope this explains it better, and of course YMMV - some rifles/twists/bullets/... are more 'prone' to SD/CE and some are less, and if you just want to bang steel plates you don't need to worry too much about SD and coriolis, but if you need surgical accuracy or need to hit the bull's eye way out there cold-bore, all of these factors should be considered.
Good luck and shoot safe,
Gun_Slinger
