Quote Originally Posted by goo View Post
so the red end points to the north magnetic pole which may or may not be 180 degrees from the south mag pole, right?
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http://www.aad.gov.au/asset/images/4...from_space.gif
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Geomagnetism - North Magnetic Pole

.. this does relate to enfields because some milsurp ammo attracts a magnet and depending on the magnetic orientation of the shooting range, a windage correction may be required.
Goo - surely thats not right :
If you make a wind-age correction for wind then you must make a magnetic-age for magnetic fields.
That leads to another question - if the wind-age allowance (say) left to right, is the same as the magentic-age correction needed right to left would they cancel each other out, and would you need to check each bullet before firing to see if it was magnetic and hence needed the magnetic-age deviation allowance ?
There are many other permutations possible - maybe you have opened up a totally new aspect to long distance target shooting, Wind-age, Magnetic-age in additon to correolis effect, bullet drop etc. What about ridge lift, wave and thermal activity ?