Originally Posted by paphil
I'm only interested in curing part of the problem in the 9 vs 3 oclock wind difference. By simply canting my scope a small amount and testing it to be about 3/4 moa , I no longer need to have a 3moa hold for one 2 mph wind and a 1 moa hold for wind in the opposite direction. Do it your own way, I have no problem with that. And Top gun, the spin drift does increase faster than the linear equations would suggest but the drop of the bullet is related to the velocity of gravity and since at 2000 yards , I'm at 93 moa, the canted allowance would be about 3.7 X the 1 moa for 1000 yards . a little over 74". If anyone has a program to dope spin drift, I'd be curious to know what it is at 2000 yards!
To work it out I would need to know the length of your bullet, the twist rate of your barrel, bullet weight, B.C. and your velocity to give you a figure.
Spin drift is a function of the above as well as time of flight and departure angle.
There are a few ways that spin drift is calculated on hand held phones and PDA's. One way is as a fraction of the standard US mil ball tables, another is by approximation calculations that simplify a lot of more complex models (As per "Shooter)". A third way is how Exbal does it by user input data from test shots but this gives a linear result as I understand it.
Its handy to know which way your program works for ELR shooting but not real important for out to 1K.
It can be measured with doplar radar.