Hey, shooting an ar for 100-500 yards (I say this so you know this isn't some complex windage question). Are you supposed to read the wind via mirage or other method at the point of the target and THEN multiply based on that little clock chart that says half value at 1 o'clock and 3/4 is multiplied by .87. So if I'm at 500 yrs and the mirage at target says about a 10 mph and the wind is at about 1 o'clock on the chart, do I do 10 x .5 to get 5 then multiple by 5 (for 500 yrs) to get 25 which I then divide by a constant?

Mirage is good. If you have a flag or thick trees on the upwind side at 200 or 300yds, even better. I prefer to see gusts and letoffs before they get to the trajectory, and after followthrough confirm with mirage.

My rule of thumb is based on Mk262 at 600yds in 10mph full value wind. 6 MOA with rifle. 7 MOA with carbine.

For carbine at 500yds with a quarter value (1:00) 10mph wind:
[Mental math]
500/600yds = 0.85.
0.85 x 7MOA = 6 MOA.
6MOA / 4 = 1.5MOA.

With 55gr ammo, go about 1.5 to 2x as much.